added moderation documentation

VARIABLES.md

@@ -2,6 +2,40 @@
 
 You can configure some of BirdsiteLIVE's settings via environment variables (those are optionnals):
 
+## Blacklisting & Whitelisting
+
+### Fediverse users and instances 
+
+Here are the supported patterns to describe Fediverse users and/or instances:
+
+* `@user@instance.ext` to describe a Fediverse user
+* `instance.ext` to describe an instance under a domain name
+* `*.instance.ext` to describe instances from all subdomains of a domain name (this doesn't include the instance.ext, if you want both you need to add both)
+
+You can whitelist or blacklist fediverses users by settings the followings variables with the above patterns separated by `;`: 
+
+* `Moderation:FollowersWhiteListing` Fediverse Whitelisting
+* `Moderation:FollowersBlackListing` Fediverse Blacklisting
+
+If the whitelisting is set, only given patterns can follow twitter accounts on the instance. 
+If blacklisted, the given patterns can't follow twitter accounts on the instance.
+If both whitelisting and blacklisting are set, only the whitelisting will be active.
+
+### Twitter users
+
+Here is the supported pattern to describe Twitter users:
+
+* `twitter_handle` to describe a Twitter user
+
+You can whitelist or blacklist twitter users by settings the followings variables with the above pattern separated by `;`: 
+
+* `Moderation:TwitterAccountsWhiteListing` Twitter Whitelisting
+* `Moderation:TwitterAccountsBlackListing` Twitter Blacklisting
+
+If the whitelisting is set, only given patterns can be followed on the instance. 
+If blacklisted, the given patterns can't be followed on the instance.
+If both whitelisting and blacklisting are set, only the whitelisting will be active.
+
 ## Logging
 
 * `Logging:Type` (default: none) set the type of the logging and monitoring system, currently the only type supported is `insights` for *Azure Application Insights* (PR welcome to support other types)
@@ -11,4 +45,41 @@ You can configure some of BirdsiteLIVE's settings via environment variables (tho
 
 * `Instance:Name` (default: BirdsiteLIVE) the name of the instance
 * `Instance:ResolveMentionsInProfiles` (default: true) to enable or disable mentions parsing in profile's description. Resolving it will consume more User's API calls since newly discovered account can also contain references to others accounts as well. On a big instance it is recommended to disable it.
-* `Instance:PublishReplies` (default: false) to enable or disable replies publishing.
+* `Instance:PublishReplies` (default: false) to enable or disable replies publishing.
+
+# Docker Compose full example
+
+In order to illustrate above variables, here is an example of an updated `docker-compose.yml` file:
+
+```diff
+version: "3"
+
+networks:
+    [...]
+
+services:
+    server:
+        image: nicolasconstant/birdsitelive:latest
+        [...]
+        environment:
+            - Instance:Domain=domain.name
+            - Instance:AdminEmail=name@domain.ext
+            - Db:Type=postgres
+            - Db:Host=db
+            - Db:Name=birdsitelive
+            - Db:User=birdsitelive
+            - Db:Password=birdsitelive
+            - Twitter:ConsumerKey=twitter.api.key
+            - Twitter:ConsumerSecret=twitter.api.key
++           - Moderation:FollowersWhiteListing=@me@my-instance.ca;friend-instance.com;*.friend-instance.com
++           - Moderation:TwitterAccountsBlackListing=douchebag;jerk_88;theRealIdiot
++           - Instance:Name=MyTwitterRelay
++           - Instance:ResolveMentionsInProfiles=false
++           - Instance:PublishReplies=true
+        networks:
+        [...]
+
+    db:
+        image: postgres:9.6
+        [...]
+```