add pr template (#180)

Author: divagant-martian

.github/pull_request_template.md

@@ -0,0 +1,17 @@
+## Description
+
+<!--
+A summary of what this pull request achieves and a rough list of changes.
+-->
+
+## Notes & open questions
+
+<!--
+Any notes, remarks or open questions you have to make about the PR. Feel free to remove this section if it's unnecessary 
+-->
+
+## Change checklist
+
+- [ ] Self-review
+- [ ] Documentation updates if relevant
+- [ ] Tests if relevant