Update docs for Busch-Jaeger 6735/6736/6737 (Koenkk#1831)

* Update docs for Busch-Jaeger 6735/6736/6737

* Busch-Jaeger 6735/6736/6737: Add note regarding HASS entities

Author: klada

docs/devices/6735_6736_6737.md

@@ -38,15 +38,56 @@ pageClass: device-page
 
 It may occur that the bottom row of the 4-gang device 6737 does not work like the other ones, i.e. does not emit the actions (see related discussion [#7009](https://github.com/Koenkk/zigbee2mqtt/discussions/7009)). The reason is not fully understood yet, however it can be worked around by unbinding all four endpoints and re-binding them manually one after another:
 
-| Source EP   | Destination   | Destination EP   | Clusters                                              |
-|-------------|---------------|------------------|-------------------------------------------------------|
-| `10`        | `Coordinator` | `1`              | 6710&nbsp;U: `LevelCtrl`<br>6711&nbsp;U: `OnOff` [^1] |
-| `11`        | `Coordinator` | `1`              | `LevelCtrl`                                           |
-| `12`        | `Coordinator` | `1`              | `LevelCtrl`                                           |
-| `13`        | `Coordinator` | `1`              | `LevelCtrl`                                           |
+| Source EP   | Destination   | Destination EP   | Clusters                                                            |
+|-------------|---------------|------------------|---------------------------------------------------------------------|
+| `10`        | `Coordinator` | `1`              | `LevelCtrl` (only for power supply or battery-operated wall switch) |
+| `11`        | `Coordinator` | `1`              | `LevelCtrl`                                                         |
+| `12`        | `Coordinator` | `1`              | `LevelCtrl`                                                         |
+| `13`        | `Coordinator` | `1`              | `LevelCtrl`                                                         |
 
 *[EP]: Endpoint
-[^1]: Depending on whether the control panel sits on a 6710&nbsp;U (power supply) or 6711&nbsp;U (relay), `OnOff` respectively `LevelCtrl` shall be used.
+
+#### Single endpoint can only be bound to one destination
+
+By default all bindings should be set up so the device reports button events through Zigbee2MQTT (except top row for dimmers/relays). You may also define custom bindings, but please keep in mind that each source endpoint may only be bound to one destination endpoint. So if you want to change the default binding for an endpoint (which corresponds to a button row) this is the recommended way:
+
+1. Unbind current destination of the particular endpoint
+2. Create a ZigBee group for the binding partners
+3. Bind the switch endpoint to the ZigBee group
+
+You should also use a ZigBee group even if you only want to bind to a single light! This way Zigbee2MQTT will continue to publish the button events, even without an explicit binding to the coordinator.
+
+#### Duplicate events for battery-operated control panel
+
+The battery-operated wall switch might be sending duplicate `action` events. In this case you may want to set up debouncing for the device:
+
+```yaml
+'0xd85devicemac':
+  debounce: 0.2
+  debounce_ignore:
+    - action:
+```
+
+This introduces a tiny lag after each button press, but you can get rid of the duplicate events if they are occuring in your environment.
+
+#### Battery-operated control panel is very hard to wake up for configuration
+
+The battery-operated devices are extremely power efficient. After pressing a button they go to deep sleep almost immediately. Therefore it can be quite hard to send a new configuration or to change bindings.
+
+For the 2-row and 4-row devices the following procedure has proven to be a good option:
+
+1. Press both buttons of the top row until the LEDs gleam permanently.
+2. Press a button in the bottom row at the same time as sending an *Unbind* request through Zigbee2MQTT for any row. This may take multiple attempts to succeed.
+3. Important: Keep this endpoint/row unbound until you are done configuring the device!
+4. Configure the endpoints/bindings according to your needs. For sending a new configuration you need to wake up the device again. Press the button in the bottom (unbound) row and this will keep the device awake for about 2 seconds.
+
+For single-row devices re-inserting the battery in the very right moment might be required when reconfiguring the switches.
+
+#### Home Assistant: device discovered both as light and switch
+
+If you are using Home Assistant auto-discovery you'll notice that the device is discovered both as a `light` entity and as a `switch` entity.
+
+**Always use the `light` entity!** The `switch` entity is only there for historic (compatibility) reasons and can be safely ignored. The main issue with the `switch` entity is that it does not update it's state when the Busch-Jaeger device is controlled directly through it's top-row rockers.
 
 ### Action values
 This device send the following `action` values in its payload: