Add tune examples and docs (PX4#431)

* Add tune examples and docs. 
* Move LEDs/tunes to first appear in getting started. Cross link from flying 101

Author: hamishwillee

assets/tunes/10_arming_failure_tune.mp3

@@ -8,6 +8,10 @@
   * [Sensors](getting_started/sensor_selection.md)
   * [Radio Systems](getting_started/rc_transmitter_receiver.md)
   * [Flight Modes](getting_started/flight_modes.md)
+  * [Vehicle Status Notifications](getting_started/vehicle_status.md)
+    * [LED Meanings](getting_started/led_meanings.md)
+    * [Tune/Sound Meanings](getting_started/tunes.md)
+    * [Preflight Checks](flying/pre_flight_checks.md)
   * [Flight Reporting](getting_started/flight_reporting.md)
 * [Basic Assembly](assembly/README.md)
   * [Mounting the Flight Controller](assembly/mount_and_orient_controller.md)
@@ -52,8 +56,6 @@
     * [Traxxas Stampede](frames_rover/traxxas_stampede.md)
 * [Flying](flying/README.md)
   * [First Flight Guidelines](flying/first_flight_guidelines.md)
-  * [LED Meanings](flying/led_meanings.md)
-  * [Preflight Checks (Internal)](flying/pre_flight_checks.md)
   * [Flying 101](flying/basic_flying.md)
     * [Landing \(Fixed Wing\)](flying/fixed_wing_landing.md)
   * [Missions](flying/missions.md)

assets/tunes/11_parachute_release.mp3

@@ -48,7 +48,7 @@ Customized screws are supposed to be M2.5 with thread length inside Cube in rang
 
 ## GPS + Compass + Safety Switch + LED {#gps}
 
-The recommended GPS modules are the *Here* and [Here+](../gps_compass/rtk_gps_hex_hereplus.md), both of which incorporate a GPS module, Compass, Safety Switch and [LEDs](../flying/led_meanings.md).
+The recommended GPS modules are the *Here* and [Here+](../gps_compass/rtk_gps_hex_hereplus.md), both of which incorporate a GPS module, Compass, Safety Switch and [LEDs](../getting_started/led_meanings.md).
 
 > **Note** The difference between the modules is that *Here+* supports centimeter level positioning via [RTK](../advanced_features/rtk-gps.md). Otherwise they are used/connected in the same way.
 

assets/tunes/12_ekf_warning.mp3

@@ -29,7 +29,7 @@ From [Drotek store](https://store.drotek.com/) (EU) :
   * [Pixhawk 3 Pro (Pack)](https://store.drotek.com/autopilots/844-pixhawk-3-pro-pack.html)
   * [Pixhawk 3 Pro](https://store.drotek.com/autopilots/821-pixhawk-pro-autopilot-8944595120557.html)
 
-From [readymaderc](www.readymaderc.com) (USA) :
+From [readymaderc](https://www.readymaderc.com) (USA) :
   * [Pixhawk 3 Pro](https://www.readymaderc.com/products/details/pixhawk-3-pro-flight-controller)
 
 ## Building Firmware

assets/tunes/13_baro_warning.mp3

@@ -93,4 +93,4 @@ All *Pixhawk-series* flight controllers support:
 * A user facing RGB *UI LED* to indicate the current *readiness to fly* status of the vehicle. This is typically a superbright I2C peripheral, which may or may not be mounted on the board (i.e. FMUv4 does not have one on board and typically uses an LED mounted on the GPS).
 * Three *Status LED*s that provide lower level power status, bootloader mode and activity, and error information.
 
-To interpret the LEDs see: [LED Meanings](../flying/led_meanings.md).
+To interpret the LEDs see: [LED Meanings](../getting_started/led_meanings.md).

assets/tunes/14_single_beep.mp3

@@ -5,12 +5,11 @@ It covers both (autopilot-assisted) manual flight and mission planning for fully
 
 [First Flight Guidelines](../flying/first_flight_guidelines.md) — Guidelines to ensure that your first flight is enjoyable, educational, and safe.
 
-[LED Meanings (Pixhawk)](../flying/led_meanings.md) — Understanding vehicle status from the status LEDs (Pixhawk-series).
-
-[Preflight Checks (Internal)](../flying/pre_flight_checks.md) — Interpreting pre-flight errors ("Why won't my vehicle arm?").
-
 [Flying 101](../flying/basic_flying.md) — How to fly a vehicle manually, using an RC Transmitter.
 
 [Missions](../flying/missions.md) — How to fly an autonomous mission.
 
 [Flight Modes](../flight_modes/README.md) — Summary table + detailed information about flight modes.
+
+
+> **Tip** [Vehicle Status Notifications](../getting_started/vehicle_status.md) can help you work out when your vehicle is ready to fly (and if not, why not).

assets/tunes/15_home_set_tune.mp3

@@ -4,6 +4,38 @@ This topic explains the basics of flying a vehicle using an [RC Transmitter](../
 
 > **Note** Before you fly for the first time you should read our [First Flight Guidelines](../flying/first_flight_guidelines.md).
 
+
+## Arm the Vehicle
+
+Before you can fly the vehicle it must first be *armed* (this will start the propellers rotating).
+
+
+> **Tip** The vehicle will not arm until it is [calibrated/configured](../config/README.md) and have a position lock. 
+  [Vehicle Status Notifications](../getting_started/vehicle_status.md) (including on-vehicle LEDs, audio notifications and *QGroundControl* updates) can tell you when the vehicle is ready to fly (and help you work out the cause when it is not ready to fly).
+
+To arm the drone, put the throttle stick in the bottom right corner.
+This will start the propellers on a multicopter.
+
+To disarm, put the throttle stick in the bottom left corner.
+Alternatively arming and disarming can also be performed in *QGroundControl* (PX4 does not require a radio control for flying autonomously).
+
+
+## Takeoff and Landing
+
+The easiest way to takeoff is to use the automatic [Takeoff mode](../flight_modes/takeoff.md) (remembering that you need to arm the vehicle before you can engage the vehicle motors). 
+To land again automatically you can use [Land](../flight_modes/land.md) or [Return](../flight_modes/return.md) modes.
+
+> **Tip** The automatic takeoff/landing modes are highly recommended, in particular for Fixed Wing vehicles. 
+
+For multicopter (and VTOL in multicopter mode) pilots can:
+
+* Take off manually by enabling [position mode](../flight_modes/README.md#assisted-modes), arming the vehicle, and then raising the throttle stick above 62.5%. 
+  Above this value all controllers are enabled and the vehicle goes to the throttle level required for hovering ([MPC_THR_HOVER](../advanced_config/parameter_reference.md#MPC_THR_HOVER)).
+* Land manually by pressing the throttle stick down until the vehicle lands and disarms (or set [COM_DISARM_LAND](../advanced_config/parameter_reference.md#COM_DISARM_LAND) > 0 to disarm automatically on landing).
+
+> **Note** If you see the vehicle "twitch" during landing (turn down the motors, and then immediately turn them back up) this is probably caused by a poor [Land Detector Configuration](../advanced_config/land_detector.md) (specifically, a poorly set [MPC_THR_HOVER](../advanced_config/parameter_reference.md#MPC_THR_HOVER)).
+
+
 ## Flight Controls/Commands
 
 All flying, including takeoff and landing, is controlled using the 4 basic commands: roll, yaw, pitch and throttle. 
@@ -55,17 +87,3 @@ The following three modes are highly recommended for new users:
 > **Tip** You can also access automatic modes through the buttons on the bottom of the *QGroundControl* main flight screen.
 
 
-## Takeoff and Landing
-
-The easiest way to takeoff is to use the automatic [Takeoff mode](../flight_modes/takeoff.md) (remembering that you need to arm the vehicle before you can engage the vehicle motors). 
-To land again automatically you can use [Land](../flight_modes/land.md) or [Return](../flight_modes/return.md) modes.
-
-> **Tip** The automatic takeoff/landing modes are highly recommended, in particular for Fixed Wing vehicles. 
-
-For multicopter (and VTOL in multicopter mode) pilots can:
-
-* Take off manually by enabling [position mode](../flight_modes/README.md#assisted-modes), arming the vehicle, and then raising the throttle stick above 62.5%. 
-  Above this value all controllers are enabled and the vehicle goes to the throttle level required for hovering ([MPC_THR_HOVER](../advanced_config/parameter_reference.md#MPC_THR_HOVER)).
-* Land manually by pressing the throttle stick down until the vehicle lands and disarms (or set [COM_DISARM_LAND](../advanced_config/parameter_reference.md#COM_DISARM_LAND) > 0 to disarm automatically on landing).
-
-> **Note** If you see the vehicle "twitch" during landing (turn down the motors, and then immediately turn them back up) this is probably caused by a poor [Land Detector Configuration](../advanced_config/land_detector.md) (specifically, a poorly set [MPC_THR_HOVER](../advanced_config/parameter_reference.md#MPC_THR_HOVER)).

assets/tunes/16_make_fs.mp3

@@ -1,47 +1,41 @@
 # First Flight Guidelines
 
-[Learning to fly](../flying/basic_flying.md) is a lot of fun! These guidelines are designed
-to ensure that your first flight experience is enjoyable, educational, and safe.
+[Learning to fly](../flying/basic_flying.md) is a lot of fun! 
+These guidelines are designed to ensure that your first flight experience is enjoyable, educational, and safe.
 
 ## Select a Good Location
 
 Selecting the right location for your first flight is critical. 
 The main things to look for are:
 
-- Make sure the space is open. No high trees, hills or buildings next
-  to it, because it will impair the GPS reception.
+- Make sure the space is open. 
+  No high trees, hills or buildings next to it, because it will impair the GPS reception.
 - Make sure no people are within 100 m / 300 feet.
-- Make sure there is nothing that you shouldn't crash onto within 100 m / 300 feet: 
-  No houses, structures, cars, water, corn fields (hard to find drones in).
+- Make sure there is nothing that you shouldn't crash onto within 100 m / 300 feet - no houses, structures, cars, water, corn fields (hard to find drones in).
+
+> **Note** 100m clearance is a good "rule of thumb", but you should also ensure you comply with flight regulations in your area.
 
 ## Bring a Pro
 
-Bring someone with experience for your first flight. Get them to help you to run through the pre-flight
-checks and let them intervene if something goes wrong!
+Bring someone with experience for your first flight. 
+Get them to help you to run through the pre-flight checks and let them intervene if something goes wrong!
 
 ## Plan the Flight
 
-Plan the flight before taking off. Make sure you know the whole route and where/how the vehicle will land.
+Plan the flight before taking off. 
+Make sure you know the whole route and where/how the vehicle will land.
 
 ## Limit the Damage
 
-Damaging property or injuring people with your UAV can have significant legal and financial 
-consequences (far in excess of the value of the UAV itself).
+Damaging property or injuring people with your UAV can have significant legal and financial consequences (far in excess of the value of the UAV itself).
 
-The UAV should always be manually flown within a safe zone where there are no obstacles or people, 
-and it must be clearly visible at all times.
+The UAV should always be manually flown within a safe zone where there are no obstacles or people, and it must be clearly visible at all times.
 
-If you start to lose control over the vehicle, and cannot bring it back under control, 
-crash it in an empty area as soon as possible.
+If you start to lose control over the vehicle, and cannot bring it back under control, crash it in an empty area as soon as possible.
 
-> **Note** It can be useful to 
-  [set a safety switch on your transmitter](../config/safety.md#safety_switch).
+> **Note** It can be useful to [set a safety switch on your transmitter](../config/safety.md#safety_switch).
   This allows you to immediately return or crash your drone if necessary.
 
-## Arm the Drone
 
-To arm the drone, put the throttle stick in the bottom right corner.
-This will start the propellers on a multicopter. To disarm, put the
-throttle stick in the bottom left corner. Alternatively arming and
-disarming can also be performed in QGroundControl (PX4 does not require
-a radio control for flying autonomously).
+
+