Add pull request template

Author: richardgaunt

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,16 @@
+## Checklist before requesting a review
+
+- [ ] I have formatted the subject to include ticket number as `Issue #123456 by drupal_org_username: Issue title`
+- [ ] I have added a link to the issue tracker
+- [ ] I have provided information in `Changed` section about WHY something was done if this was not a normal implementation
+- [ ] I have performed a self-review of my code
+- [ ] I have commented my code, particularly in hard-to-understand areas
+- [ ] I have added tests that prove my fix is effective or that my feature works
+- [ ] I have run new and existing relevant tests locally with my changes, and they passed
+- [ ] I have provided screenshots, where applicable
+
+## Changed
+
+1.
+
+## Screenshots