docs: fix message command example to use ctx.args()

Author: twlite

apps/website/docs/guide/02-commands/04-message-commands.mdx

@@ -53,7 +53,7 @@ export const command: CommandData = {
 };
 
 export const message: MessageCommand = async (ctx) => {
-  const args = ctx.message.args(); // string[]
+  const args = ctx.args(); // string[]
 };
 ```