Create pull_request_template.md

Author: phip1611

.github/PULL_REQUEST_TEMPLATE.md

@@ -4,4 +4,4 @@
 - [ ] Sensible git history (for example, squash "typo" or "fix" commits). See the
       [Rewriting History](https://git-scm.com/book/en/v2/Git-Tools-Rewriting-History) guide for
       details.
-- [ ] updated the changelog (if necessary)
+- [ ] update the changelog (if necessary)