Add docs for the Command Service

docs/guides/samples/dependency_module.cs

@@ -0,0 +1,28 @@
+using Discord;
+using Discord.Commands;
+
+[Module]
+public class ModuleA
+{
+    private DiscordSocketClient client;
+    private ISelfUser self;
+
+    public ModuleA(IDiscordClient c, ISelfUser s)
+    {
+        if (!(c is DiscordSocketClient)) throw new InvalidOperationException("This module requires a DiscordSocketClient");
+        client = c as DiscordSocketClient;
+        self = s;
+    }
+}
+
+public class ModuleB
+{
+    private IDiscordClient client;
+    private CommandService commands;
+    
+    public ModuleB(CommandService c, IDependencyMap m)
+    {
+        commands = c;
+        client = m.Get<IDiscordClient>();
+    }
+}