Add PR template

Author: jerry-git

.github/pull_request_template.md

@@ -0,0 +1,9 @@
+## Description
+
+A short description about the changes in this pull request. If the pull request is related to some issue, mention it here.
+
+## Checklist
+
+- [] Tests covering the new functionality have been added
+- [] Documentation has been updated OR the changes are too minor to be documented
+- [] The Changes are listed in the `CHANGELOG.md` OR the changes are insignificant