Update pull request template links

Author: SimonBaeumer

.github/PULL_REQUEST_TEMPLATE.md

@@ -3,6 +3,6 @@ Fixes #
 ## Checklist
 
  - [ ] Added unit / integration tests for windows, macOS and Linux? 
- - [ ] Added a changelog entry in [CHANGELOG.md](../CHANGELOG.md)?
- - [ ] Updated the documentation ([README.md](../README.md), [docs](../docs))?
+ - [ ] Added a changelog entry in [CHANGELOG.md](https://github.com/commander-cli/commander/blob/master/CHANGELOG.md)?
+ - [ ] Updated the documentation ([README.md](https://github.com/commander-cli/commander/blob/master/README.md), [docs](https://github.com/commander-cli/commander/blob/master/docs))?
  - [ ] Does your change work on `Linux`, `Windows` and `macOS`?