Add PR template (#3)

* Add PR template

Signed-off-by: Kenji Miyake <kenji.miyake@tier4.jp>

* Update PULL_REQUEST_TEMPLATE.md

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,41 @@
+## Related Links
+
+<!-- Please write related links to GitHub/Jira/Slack/etc. -->
+
+## Description
+
+<!-- Describe what this PR changes. -->
+
+## Remarks
+
+<!-- Write remarks as you like if you need them. -->
+
+## Pre-Review Checklist for the PR Author
+
+**PR Author should check the checkboxes below when creating the PR.**
+
+- [ ] Code is properly formatted
+- [ ] Assign PR to reviewer
+
+## Checklist for the PR Reviewer
+
+**Reviewers should check the checkboxes below before approval.**
+
+- [ ] Commits are properly organized and messages are according to the guideline
+- [ ] Code is properly formatted
+- [ ] PR title describes the changes
+
+## Post-Review Checklist for the PR Author
+
+**PR Author should check the checkboxes below before merging.**
+
+- [ ] All open points are addressed and tracked via issues or tickets
+- [ ] Write [release notes][release-notes]
+
+## CI Checks
+
+- **Build and test for PR**: Required to pass before the merge.
+- **Check spelling**: NOT required to pass before the merge. It is up to the reviewer(s). See [here][spell-check-dict] if you want to add some words to the spell check dictionary.
+
+[release-notes]: https://tier4.atlassian.net/wiki/spaces/AIP/pages/563774416
+[spell-check-dict]: https://github.com/tier4/autoware-spell-check-dict#how-to-contribute