Adds new chores to the pull request template for documentation and updating the changelog

Author: ndgrigorian

.github/pull_request_template.md

@@ -3,4 +3,6 @@
 - [ ] Have you tested your changes locally for CPU and GPU devices?
 - [ ] Have you made sure that new changes do not introduce compiler warnings?
 - [ ] Have you checked performance impact of proposed changes?
+- [ ] Have you added documentation for your changes, if necessary?
+- [ ] Have you added your changes to the changelog?
 - [ ] If this PR is a work in progress, are you opening the PR as a draft?