Add customizable Bot status (#599)

Co-authored-by: Max Isom <codetheweb@users.noreply.github.com>
Co-authored-by: Max Isom <hi@maxisom.me>

README.md

@@ -95,6 +95,38 @@ services:
 
 By default, Muse limits the total cache size to around 2 GB. If you want to change this, set the environment variable `CACHE_LIMIT`. For example, `CACHE_LIMIT=512MB` or `CACHE_LIMIT=10GB`.
 
+### Custom Bot Status
+
+In the default state, Muse has the status "Online" and the text "Listening to Music". You can change the status through environment variables:
+
+- `BOT_STATUS`:
+  - `online` (Online)
+  - `idle` (Away)
+  - `dnd` (Do not Disturb)
+
+- `BOT_ACTIVITY_TYPE`:
+  - `PLAYING` (Playing XYZ)
+  - `LISTENING` (Listening to XYZ)
+  - `WATCHING` (Watching XYZ)
+  - `STREAMING` (Streaming XYZ)
+
+- `BOT_ACTIVITY`: the text that follows the activity type
+
+- `BOT_ACTIVITY_URL` If you use `STREAMING` you MUST set this variable, otherwise it will not work! Here you write a regular YouTube or Twitch Stream URL.
+
+#### Examples
+
+**Muse is watching a movie and is DND**:
+- `BOT_STATUS=dnd`
+- `BOT_ACTIVITY_TYPE=WATCHING`
+- `BOT_ACTIVITY=a movie`
+
+**Muse is streaming Monstercat**:
+- `BOT_STATUS=online`
+- `BOT_ACTIVITY_TYPE=STREAMING`
+- `BOT_ACTIVITY_URL=https://www.twitch.tv/monstercat`
+- `BOT_ACTIVITY=Monstercat`
+
 ### Bot-wide commands
 
 If you have Muse running in a lot of guilds (10+) you may want to switch to registering commands bot-wide rather than for each guild. (The downside to this is that command updates can take up to an hour to propagate.) To do this, set the environment variable `REGISTER_COMMANDS_ON_BOT` to `true`.