fix(release): keep the manifest self-documenting

The placeholder this file replaces carried a $comment saying it is generated
and that an empty downloads array is the pre-release state rather than a bug.
The generator dropped it on the first real release, which is exactly when the
next reader needs it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/release-manifest.py

@@ -149,6 +149,15 @@ def main():
     args.out.mkdir(parents=True, exist_ok=True)
 
     releases = {
+        # Carried through from the pre-release placeholder this file replaces:
+        # it is the only thing telling the next reader that the file is generated
+        # and that an empty downloads array is a meaningful state, not a bug.
+        "$comment": (
+            "Generated by scripts/release-manifest.py in the launcher repository; "
+            "do not edit by hand. The site reads nothing else about launcher "
+            "downloads. An empty downloads array is the pre-release state and "
+            "renders as 'not yet released' rather than a broken button."
+        ),
         "version": version,
         "publishedAt": published,
         "notesUrl": args.notes_url,