change checklist as header

Author: softwareengineerprogrammer

.github/pull_request_template.md

@@ -11,9 +11,11 @@ and any other relevant information.*
 
 ---
 
-**Change Checklist**:
+# Change Checklist
 
-Before merging:
+Observe the following checklist items before and after merging, as applicable.
+
+**Before merging:**
 1. [ ] I certify that I am a human and I have manually verified the correctness of the changes in this PR.
 1. [ ] Add a CHANGELOG entry if your change includes a new version[^new-version-footnote] ([example](https://github.com/NREL/GEOPHIRES-X/commit/15e10e5c3c08633a16645e41dfb7e8131805483f)). RST Template:
 ```restructuredtext
@@ -22,7 +24,7 @@ M.m.P: `TITLE <https://github.com/NREL/GEOPHIRES-X/pull/PR-NUMBER>`__ | `release
 
 [^new-version-footnote]: See [versioning notes](https://github.com/NREL/GEOPHIRES-X/blob/main/CHANGELOG.rst#versioning-notes) and [version management docs](https://github.com/NREL/GEOPHIRES-X/blob/main/CONTRIBUTING.rst#version-management).
 
-After merging:
+**After merging:**
 1. [ ] Push tag(s) to GitHub: `git push origin refs/tags/vM.m.P`
 1. [ ] Post a change announcement to the [GEOPHIRES Change Announcements Discussion](https://github.com/NREL/GEOPHIRES-X/discussions/428) ([example](https://github.com/NREL/GEOPHIRES-X/discussions/428#discussioncomment-14593405)). Markdown template:
 ```markdown