[Misc] Add release note draft to PR template (vllm-project#23598)

Signed-off-by: simon-mo <[email protected]>

Author: simon-mo

.github/PULL_REQUEST_TEMPLATE.md

@@ -7,8 +7,6 @@ PLEASE FILL IN THE PR DESCRIPTION HERE ENSURING ALL CHECKLIST ITEMS (AT THE BOTT
 
 ## Test Result
 
-## (Optional) Documentation Update
-
 ---
 <details>
 <summary> Essential Elements of an Effective PR Description Checklist </summary>
@@ -17,6 +15,7 @@ PLEASE FILL IN THE PR DESCRIPTION HERE ENSURING ALL CHECKLIST ITEMS (AT THE BOTT
 - [ ] The test plan, such as providing test command.
 - [ ] The test results, such as pasting the results comparison before and after, or e2e results
 - [ ] (Optional) The necessary documentation update, such as updating `supported_models.md` and `examples` for a new model.
+- [ ] (Optional) Release notes update. If your change is user facing, please update the release notes draft in the [Google Doc](https://docs.google.com/document/d/1YyVqrgX4gHTtrstbq8oWUImOyPCKSGnJ7xtTpmXzlRs/edit?tab=t.0).
 </details>
 
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