Fix spelling/grammar/formatting of volunteer roles descriptions

apps/volunteer/data/roles/bar.yml

@@ -9,9 +9,9 @@ full_description_md: |
   2. It's a great way to learn how to work on a bar and get experience if you ever fancy a career change! We'll teach you everything you need to know on the job, it's really easy once you get started.
   3. Usually the bar shifts are pretty short so they're easy to fit in with other things you might want to do, you can even pop back later and help out if there's a big queue, and help get your friends served quicker.
   
-  Working behind the bar is loads of fun, its not hard work, and without lovely people like you we'd have no bar, so volunteer for a shift or two, or even three!
+  Working behind the bar is loads of fun, it's not hard work, and without lovely people like you we'd have no bar, so volunteer for a shift or two, or even three!
 
-  **For legal reasons your must be over 18 and complete [this short online course](https://www.emfcamp.org/volunteer/bar-training) before starting a shift.**
+  **For legal reasons you must be over 18 and complete [this short online course](https://www.emfcamp.org/volunteer/bar-training) before starting a shift.**
 over_18_only: true
 requires_training: true
 role_notes: Requires training, over 18s only.

apps/volunteer/data/roles/cybar.yml

@@ -16,7 +16,7 @@ full_description_md: |
   
   Working behind the bar is loads of fun, it's not hard work, and without lovely people like you we'd have no bar, so volunteer for a shift or two, or even three!
 
-  **For legal reasons your must be over 18 and complete [this short online course](https://www.emfcamp.org/volunteer/bar-training) before starting a shift.**
+  **For legal reasons you must be over 18 and complete [this short online course](https://www.emfcamp.org/volunteer/bar-training) before starting a shift.**
 over_18_only: true
 requires_training: true
 role_notes: Requires training, over 18s only.

apps/volunteer/data/roles/green_room_runner.yml

@@ -3,4 +3,4 @@ description: Make sure speakers get where they need to be with what they need.
 full_description_md: |
   Make sure speakers get where they need to be with what they need.
   
-  You'll be based in the Green Room where you'll greet speakers and get them ready to go on stage. You'll also help out the Content Team with any adhoc tasks that come up.
+  You'll be based in the Green Room where you'll greet speakers and get them ready to go on stage. You'll also help out the Content Team with any ad-hoc tasks that come up.

apps/volunteer/data/roles/herald.yml

@@ -3,4 +3,6 @@ description: Introduce talks and manage speakers at stage.
 full_description_md: |
   Introducing talks, and making any announcements that are needed between talks.
   
-  You'll be helping speakers get ready, introducing them on stage and checking to make sure any announcements that need to happen are made between talks. If you have any talks you'd particularly like to see you can volunteer for a shift on the appropriate stage.\n\nIf you've never walked on stage before then don't be put off; we'll be running some training to walk through the role and make sure everyone is comfortable. In fact many of us would identify as introverts.
+  You'll be helping speakers get ready, introducing them on stage and checking to make sure any announcements that need to happen are made between talks. If you have any talks you'd particularly like to see you can volunteer for a shift on the appropriate stage.
+
+  If you've never walked on stage before then don't be put off; we'll be running some training to walk through the role and make sure everyone is comfortable. In fact many of us would identify as introverts.

apps/volunteer/data/roles/phone_helpdesk_assistant.yml

@@ -1,4 +1,4 @@
 name: Phone Helpdesk Assistant 
 description: ""
 full_description_md: |
-  Be the friendly face of the phone team for a few hours, helping attendees with their phone (DECT/SIP/GSM/POTS) related questions, we'll give you some brief training and access to a couple of systems to check and update things, there will be other people from the phone team around to back you up, we're happy to explain how the sytem (mostly) works too.
+  Be the friendly face of the phone team for a few hours, helping attendees with their phone (DECT/SIP/GSM/POTS) related questions. We'll give you some brief training and access to a couple of systems to check and update things, there will be other people from the phone team around to back you up and we're happy to explain how the system (mostly) works too.