Add PR template

Author: garyb

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,12 @@
+**Description of the change**
+
+Clearly and concisely describe the purpose of the pull request. If this PR relates to an existing issue or change proposal, please link to it. Include any other background context that would help reviewers understand the motivation for this PR.
+
+---
+
+**Checklist:**
+
+- [ ] Added the change to the changelog's "Unreleased" section with a reference to this PR (e.g. "- Made a change (#0000)")
+- [ ] Linked any existing issues or proposals that this pull request should close
+- [ ] Updated or added relevant documentation
+- [ ] Added a test for the contribution (if applicable)