Add brigardier example to the guide

guide/docs/commands/brigardier_example.md

@@ -0,0 +1,19 @@
+The following command illustrates how to use commands, subcommands, arguments and the command context.
+
+```kotlin
+command("gaming") {
+    literal("set") {
+        argument("state", BoolArgumentType.bool()) {
+            simpleSuggests { listOf(true, false) }
+            simpleExecutes {
+                if (it.getArgument("state"))
+                    it.source.bukkitSender.sendMessage("yoo gaming has been activated")
+                else {
+                    it.source.player.kill()
+                    it.source.player.sendText("gaming disabled") { color = KColors.INDIANRED }
+                }
+            }
+        }
+    }
+}
+```