[DOCS] Group commands example (#2246)

* add Group Command Examples to int_framework intro

* update subcommad group's name

* added some comments t othe example code

* fixed naming

* added spaces in comments

docs/guides/int_framework/samples/intro/groupmodule.cs

@@ -0,0 +1,21 @@
+// You can put commands in groups
+[Group("group-name", "Group description")]
+public class CommandGroupModule : InteractionModuleBase<SocketInteractionContext>
+{
+    // This command will look like
+    // group-name ping
+    [SlashCommand("ping", "Get a pong")]
+    public async Task PongSubcommand()
+        => await RespondAsync("Pong!");
+    
+    // And even in sub-command groups
+    [Group("subcommand-group-name", "Subcommand group description")]
+    public class SubСommandGroupModule : InteractionModuleBase<SocketInteractionContext>
+    {
+        // This command will look like
+        // group-name subcommand-group-name echo
+        [SlashCommand("echo", "Echo an input")]
+        public async Task EchoSubcommand(string input)
+            => await RespondAsync(input);
+    }
+}