Clarify that only the issue author's 👎 reaction prevents auto-closure

The bot comment told users to "👎 this comment" without specifying whose
reaction is checked. Since hasCreatorThumbsDown only looks at the issue
author's reaction, maintainers or other community members reacting with
👎 would have no effect. Update the comment text to set correct
expectations.

Author: smorimoto

scripts/comment-on-duplicates.sh

@@ -91,7 +91,7 @@ done
 
 BODY+=$'\n'"This issue will be automatically closed as a duplicate in 3 days."$'\n\n'
 BODY+="- If your issue is a duplicate, please close it and 👍 the existing issue instead"$'\n'
-BODY+="- To prevent auto-closure, add a comment or 👎 this comment"$'\n'
+BODY+="- To prevent auto-closure, add a comment or 👎 this comment (only the issue author's reaction is checked)"$'\n'
 
 # Post the comment
 gh issue comment "$BASE_ISSUE" --repo "$REPO" --body "$BODY"