github: update pull request template

Signed-off-by: Yuxuan Shui <[email protected]>

.github/pull_request_template.md

@@ -1,7 +1,13 @@
-<!-- Please enable "Allow edits from maintainers" so we can make necessary changes to your PR -->
+## Summary
 
-# Changelog
+<!-- If your pull request includes many commits, please provide a summary,
+     otherwise delete this section. We prefer you put detailed descriptions
+     in the commit messages. -->
 
-<!-- If you want to add a changelog entry for this PR, write it here; otherwise delete this section -->
-* Category: (Bug fixes, new features, etc.)
-* Description: (Describe changes made)
+## Checklist
+
+- [ ] Enable "Allow edits from maintainers". (So we can make necessary changes).
+- [ ] Add changelog entries to commit message when appropriate. These will be included in release announcements.
+  Changelog entries should be formatted like this in the commit message:
+  `Changelog: BugFix: Stop picom from summoning the Great Old Ones.`
+  The entry must start with `Changelog: `, followed by a category (`BugFix: ` in this case), then a short description of the changes in the commit.