Update PR template given we now use it for commit descriptions.

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,12 +1,23 @@
-## Description
+Include a summary of the changes and the related issue if any.
 
-Fixes #(issue number)
+A good description is a paragraph or so describing the changes you made and the
+motivation. You may follow this with a few bullets for specific changes, but
+try to keep it concise.
 
-[Please include a summary of the changes and the related issue.]
+e.g.
 
+Title: [RL] Fix loss: use global token normalization instead of per-example
 
-## Checklist
+"""
+This fixes a regression in the DAPO loss computation by switching
+from per-example normalization (/ n_i) back to global token
+normalization (/ N). Per-example normalization gives shorter responses
+disproportionately more gradient weight, which hurts math reasoning
+tasks where correct answers often require detailed, longer derivations.
+Global normalization weights all examples equally regardless of response
+length.
+"""
 
-- [ ] You ran `uv run python infra/pre-commit.py --all-files` to lint/format your code
-- [ ] You ran 'pytest' to test your code
-- [ ] Delete this checklist
+<!-- If this PR addresses an existing issue, include "Fixes #XXXX" below. -->
+<!-- For ongoing work, PRs should reference an existing issue. Delete this comment when done. -->
+Fixes #