Add a pull request template

Author: jorisdral

.github/pull_request_template.md

@@ -0,0 +1,10 @@
+# Description
+
+Add your description here, if it fixes a particular issue please provide a
+[link](https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword=)
+to the issue.
+
+# Checklist
+
+- [ ] Read our contribution guidelines at [CONTRIBUTING.md](https://github.com/IntersectMBO/lsm-tree/blob/main/CONTRIBUTING.md), and make sure that this PR complies with the guidelines.
+