chore(docs): add PR template

Author: omarabid

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,9 @@
+<!--
+Thanks for helping out!
+
+Please link the appropriate issue from your PR.
+
+If you don't have an issue, we'd recommend starting with one first so the PR can focus on the
+implementation (unless its an obvious bug or documentation fix that will have
+little conversation).
+-->