update PR template

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,6 +1,4 @@
 
-# Pull Request Template
-
 ## Description
 
 Please include a summary of the change.
@@ -9,6 +7,6 @@ To increment major or minor changes add #major or #minor to the PR description.
 
 
 ## Checklist:
-- [ ] Unit tests are added to cover the changes.
-- [ ] The changes are mentioned in the documentation.
-- [ ] CHANGELOG.md is updated (skip if the change is not important for the changelog).
+- [ ] Unit tests are added to cover the changes (skip if not applicable).
+- [ ] The changes are mentioned in the documentation (skip if not applicable).
+- [ ] CHANGELOG file is updated (skip if not applicable).