Update pull_request_template.md

Author: egil

.github/pull_request_template.md

@@ -7,12 +7,12 @@
 ### PR meta checklist
 - [ ] Pull request is targeting at `DEV` branch.
 - [ ] Pull request is linked to all related issues, if any.
-- [ ] I have read the _CONTRIBUTING_ document.
+- [ ] I have read the [CONTRIBUTING.md](/CONTRIBUTING.md) document.
 
 ### Content checklist
 - [ ] My code follows the code style of this project and AspNetCore coding guidelines.
 - [ ] My change requires a change to the documentation.
   - [ ] I have updated the documentation accordingly.
-- [ ] I have updated the appropriate sub section in the _CHANGELOG.md_.
+- [ ] I have updated the appropriate sub section in the [CHANGELOG.md](/CHANGELOG.md).
 - [ ] I have added, updated or removed tests to according to my changes.
   - [ ] All tests passed.