Add checkbox to pull request template with instructions to update the changelog/readme if needed (#159)

Co-authored-by: Simon Beal <[email protected]>

Author: muddyfish

.github/pull_request_template.md

@@ -7,6 +7,9 @@
 <!-- Provide details that would help an engineer who is unfamiliar with this part of the code. -->
 <!-- Please confirm there is no breaking change, or call out any behavior changes you think are necessary. -->
 
+
+- [ ] I have updated the CHANGELOG or README if appropriate
+
 ## Related items
 <!-- Please add related pull requests or Github issues. -->