add mini apps asset generator tip to manifest (#534)

Author: hughescoin

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

@@ -61,6 +61,10 @@ Set `"noindex": true` for development or staging environments to prevent search
 Changes to the manifest take effect when you redeploy your Mini App and repost it. The platform re-indexes the updated configuration and applies changes to search, discovery, and embed rendering.
 </Warning>
 
+<Tip>
+Use the [Mini App Assets Generator](https://www.miniappassets.com/) to generate properly formatted icons, splash screens, and images that meet the requirements for both Base App and Farcaster mini apps.
+</Tip>
+