Remove CHANGELOG.md from the PR template (#471)

This repo only has a `CHANGES.md` and `CHANGELOG.md` is not applicable.
This PR removes the `CHANGELOG.md` from the template.

Author: bessbd

.github/PULL_REQUEST_TEMPLATE.md

@@ -5,7 +5,7 @@ Thanks for your hard work, please ensure all items are complete before opening.
 
 - [ ] Tick to sign-off your agreement to the [Developer Certificate of Origin (DCO) 1.1](../blob/master/DCO1.1.txt)
 - [ ] Added tests for code changes _or_ test/build only changes
-- [ ] Updated the change log file (`CHANGES.md`|`CHANGELOG.md`) _or_ test/build only changes
+- [ ] Updated the change log file (`CHANGES.md`) _or_ test/build only changes
 - [ ] Completed the PR template below:
 
 ## Description