docs(contributing): add pre-commit setup

Author: Lee-W

docs/contributing.md

@@ -11,10 +11,11 @@ If you're a first-time contributor, you can check the issues with [good first is
 1. Fork [the repository](https://github.com/commitizen-tools/commitizen).
 2. Clone the repository from your GitHub.
 3. Setup development environment through [poetry](https://python-poetry.org/) (`poetry install`).
-4. Check out a new branch and add your modification.
-5. Add test cases for all your changes.
+4. Setup [pre-commit](https://pre-commit.com/) hook (`pre-commit install -t pre-commit -t pre-push`)
+5. Check out a new branch and add your modification.
+6. Add test cases for all your changes.
    (We use [CodeCov](https://codecov.io/) to ensure our test coverage does not drop.)
-6. Use [commitizen](https://github.com/commitizen-tools/commitizen) to do git commit.
-7. Run `./scripts/reformat` and `./scripts/test` to ensure you follow the coding style and the tests pass.
-8. Update `READMD.md` and `CHANGELOG.md` for your changes.
-9. Send a [pull request](https://github.com/commitizen-tools/commitizen/pulls) 🙏
+7. Use [commitizen](https://github.com/commitizen-tools/commitizen) to do git commit.
+8. Run `./scripts/reformat` and `./scripts/test` to ensure you follow the coding style and the tests pass.
+9. Update `READMD.md` and `CHANGELOG.md` for your changes.
+10. Send a [pull request](https://github.com/commitizen-tools/commitizen/pulls) 🙏