add highlighting to addMiniApp

Author: hughescoin

docs/mini-apps/core-concepts/notifications.mdx

@@ -105,7 +105,7 @@ You will receive webhook events when users enable or disable notifications for y
   <Step title="Prompt users to add your Mini App">
     Use the `addMiniApp()` hook to prompt users to add your Mini App
 
-    ```tsx page.tsx
+    ```tsx page.tsx highlight={11, 25-27}
     "use client";
 
     import { sdk } from "@farcaster/miniapp-sdk";