This PR clarifies the release notes title format in the release
checklist documentation.
**Changes:**
- Add explicit section explaining title format for -rc1, subsequent RCs,
and stable releases
- Make it clear that titles should include both the RC suffix AND the
date (e.g., "Lean 4.7.0-rc1 (2024-03-15)")
- Update example to use realistic date format instead of YYYY-MM-DD
- Clarify that only content is written for -rc1, subsequent releases
just update the title
This addresses confusion about whether RC release notes should include
the date in the title.
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Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
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