Add help command

src/Bot/BotCommands.fs

@@ -25,4 +25,21 @@ module BotCommands =
            match channelGotAdded with
            | true  -> ctx.RespondAsync "This is now my channel :)"   |> ignore
            | false -> ctx.RespondAsync "This is now your channel (:" |> ignore
-      } |> Async.StartAsTask :> Task 
+      } |> Async.StartAsTask :> Task 
+
+    [<Command("help")>]
+    member public self.help(ctx:CommandContext) =
+      async { 
+        ctx.RespondAsync 
+        """
+        Hello! This is the WikiMathBot
+
+        Here are some commands you can use:
+        !echo <something> - Test whether I'm awake or not
+        !help             - Display this message
+        !hi               - Same as !echo
+        !toggle           - Toggle my notifications in this channel
+        """ 
+        |> ignore
+      }
+      |> Async.StartAsTask :> Task