docs: update pull request template for reviewer

.github/pull_request_template.md

@@ -9,10 +9,11 @@
 
 ## Checklist
 I have read through the [contributing guidelines](https://bigtree.readthedocs.io/en/stable/home/contributing/) and ensured that
+- [ ] I have added a descriptive title for this pull request.
 - [ ] I have followed the convention and standards, and my code is checked for style and correctness.
 - [ ] I have added test cases and ensured unit tests passed and code coverage is 100%.
 - [ ] I have ensured documentation and code docstrings are up-to-date.
 
 ## Checklist (for reviewer)
-- [ ] I have added label (breaking / enhancement / bug / documentation) for this pull request, if applicable.
-- [ ] I will ensure this change is captured in *CHANGELOG.md* file.
+- [ ] I have added label (breaking / enhancement / bug / documentation) to this pull request, if applicable.
+- [ ] I will ensure this change is captured in the *CHANGELOG.md* file.