Add docs for the Command Service

docs/guides/samples/command_handler.cs

@@ -0,0 +1,52 @@
+using System.Threading.Tasks;
+using System.Reflection;
+using Discord;
+using Discord.Commands;
+
+public class Program
+{
+    private CommandService commands;
+    private DiscordSocketClient client;
+
+    static void Main(string[] args) => new Program().Start().GetAwaiter().GetResult();
+
+    public async Task Start()
+    {
+        client = new DiscordSocketClient();
+        commands = new CommandService();
+
+        string token = "bot token here";
+
+        await InstallCommands();
+
+        await client.LoginAsync(TokenType.Bot, token);
+        await client.ConnectAsync();
+
+        await Task.Delay(-1);
+    }
+
+    public async Task InstallCommands()
+    {
+        // Hook the MessageReceived Event into our Command Handler
+        client.MessageReceived += HandleCommand;
+		// Discover all of the commands in this assembly and load them.
+        await commands.LoadAssembly(Assembly.GetEntryAssembly());
+    }
+    public async Task HandleCommand(IMessage msg)
+	{
+		// Internal integer, marks where the command begins
+		int argPos = 0;
+		// Get the current user (used for Mention parsing)
+		var currentUser = await client.GetCurrentUserAsync();
+		// Determine if the message is a command, based on if it starts with '!' or a mention prefix
+		if (msg.HasCharPrefix('!', ref argPos) || msg.HasMentionPrefix(currentUser, ref argPos)) 
+		{
+			// Execute the command. (result does not indicate a return value, 
+			// rather an object stating if the command executed succesfully)
+			var result = await _commands.Execute(msg, argPos);
+			if (!result.IsSuccess)
+				await msg.Channel.SendMessageAsync(result.ErrorReason);
+		}
+	}
+
+}