add sign manifest to launch checklist

Author: hughescoin

docs/mini-apps/quickstart/launch-checklist.mdx

@@ -22,7 +22,7 @@ Authenticate when it unlocks value, not before. Fast, optional sign‑in keeps m
 
 Your manifest powers saving, discovery, and rich embeds. A strong manifest includes complete fields, valid assets, and `noindex: true` during testing.
 
-<Card title="Manifest" icon="file" href="/mini-apps/features/manifest" />
+<Card title="Sign Your Manifest" icon="signature" href="/mini-apps/features/sign-manifest" />
 
 ## Embeds & Previews