Add PR template (#623)

.github/pull_request_template.md

@@ -0,0 +1,16 @@
+## Description
+
+_Summarize the changes included in this pull request. What is the current behavior and what is the updated/expected behavior of this PR? Include relevant context, and reasoning behind architectural/design decisions._
+
+### Other changes
+
+_Describe any minor or "drive-by" changes here._
+
+### Optional section
+
+* Reviewers, please pay special attention to...
+* If this PR exceeds 500 lines, please explain why
+
+## Tested
+
+_How did you test these changes? Provide instructions so reviewers can reproduce if desired. Please also list any relevant details for your test configuration._