Updated the PR template checklist

.github/PULL_REQUEST_TEMPLATE.md

@@ -19,7 +19,7 @@
 ### :thinking: Checklist before submitting
 
 - [ ] I made sure all projects build.
-- [ ] I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy.
+- [ ] I updated pubspec.yaml with an appropriate new version according to the [pub versioning philosophy](https://dart.dev/tools/pub/versioning).
 - [ ] I updated CHANGELOG.md to add a description of the change.
 - [ ] I followed the style guide lines ([code style guide](https://github.com/Baseflow/flutter-permission-handler/blob/develop/CONTRIBUTING.md)).
 - [ ] I updated the relevant documentation.