Add VoiceRoleSync documentation; fix occasional error

Module/VoiceRoleSync/VoiceRoleSync.cs

@@ -26,6 +26,7 @@ namespace Noikoio.RegexBot.Module.VoiceRoleSync
             // Gather data.
             if (!(argUser is SocketGuildUser user)) return; // not a guild user
             var settings = GetState<GuildSettings>(user.Guild.Id);
+            if (settings == null) return; // not enabled here
             var deafened = after.IsDeafened || after.IsSelfDeafened;
             var (settingBefore, settingAfter) = settings.GetChannelSettings(before.VoiceChannel, after.VoiceChannel);
 

docs/serverdef.md

@@ -31,3 +31,4 @@ The following is a list of accepted members within a server definition.
 * [EntryAutoRole](entryautorole.html) - See respective page.
 * [ModCommands](modcommands.html) - See respective page.
 * [ModLogs](modlogs.html) - See respective page.
+* [VoiceRoleSync](voicerolesync.html) - See respective page.

docs/voicerolesync.md

@@ -0,0 +1,18 @@
+## VoiceRoleSync
+
+VoiceRoleSync directs the bot to apply specific roles to users when they are listening in to a voice channel.
+
+Sample within a [server definition](serverdef.html):
+```
+"VoiceRoleSync": {
+	//"1000001::General": "1000002::In General VC",
+	//"1000003::Video Games": "1000004::In Gaming VC"
+	"1000001": "1000002",
+	"1000003": "1000004"
+}
+```
+
+### Definition structure
+A list of voice channels and their respective roles are defined in a `VoiceRoleSync` object. They are defined as JSON properties, with the name portion (before the colon) representing the voice channel and the value portion (after the colon) representing the role to be associated.
+
+At the moment, only voice channel and role ID values are accepted in this configuration. EntityList-like names will be supported at a later date.