fix links in pull request template

pull_request_template.md

@@ -6,8 +6,10 @@ Please add a description of the changes proposed in the pull request.
 - [ ] @mentions of the person or team responsible for reviewing proposed changes.
 - [ ] This pull request has a descriptive title.
 - [ ] Code is written according to the [guidelines](http://cnl.sogang.ac.kr/cnlab/lectures/programming/matlab/Richard_Johnson-MatlabStyle2_book.pdf).
-- [ ] The checks by [MISS_HIT style checker and linter](https://github.com/EcoExtreML/STEMMUS_SCOPE/blob/main/CONTRIBUTING.md#follow-matlab-style-guidelines), below the pull request, are successful (green).
+- [ ] The checks by [MISS_HIT style checker and
+  linter](./docs/CONTRIBUTING.md#miss_hit-checks), below the pull request, are
+  successful (green).
 - [ ] Documentation is available.
 - [ ] Add changes to the [changelog file](CHANGELOG.md) under section `Unreleased`.
-- [ ] Model runs successfully.
+- [ ] Model runs successfully, see [tests](./docs/CONTRIBUTING.md#testing-new-changes).
 - [ ] Ask a meinatainer to re-generate exe file if matlab codes are changed. About how to create an exe file, see [exe readme](https://github.com/EcoExtreML/STEMMUS_SCOPE/blob/main/run_model_on_snellius/exe/README.md).