docs: comment instructions for PR template (#1710)

* docs: comment instructions for PR template

Updated the pull request template to include comment descriptions for each section.

* Update pull request template for clarity

Clarify the purpose of the summary section in the pull request template.

* docs: reduce verbosity of UI section

* docs: remove excess punctuation & syntax

Ending heading with hashes is redundant. Heading text needs no colon; colon is for content text that introduces more content.

* docs: reduce all comments to one line

Author: wesleyboar

.github/pull_request_template.md

@@ -1,20 +1,37 @@
-## Overview: ##
+## Overview
 
-## PR Status: ##
+<!--
+1–3 sentences stating what problem this solves and what you changed at a high level. Example: "Adds/Fixes X, when Y, via Z."
+-->
+
+## PR Status
 
 * [X] Ready.
 * [ ] Work in Progress.
 * [ ] Hold.
 
-## Related Jira tickets: ##
+## Related Links
 
 * [DES-XXXX](https://tacc-main.atlassian.net/browse/DES-XXXX)
 
-## Summary of Changes: ##
+## Summary of Changes
+
+<!--
+Details (perhaps excluded from the simpler overview) that may be clearer as text than reading the diff.
+-->
+
+## Testing Steps
+
+1. …
+
+## UI
 
-## Testing Steps: ##
-1. 
+<!--
+Any screenshots or videos to illustrate the change: https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/attaching-files
+-->
 
-## UI Photos:
+## Notes
 
-## Notes: ##
+<!--
+Optional: gotchas, known limitations, further context, etc.
+-->