docs(docs/contributing.md): update the contributing.md, add session Install before contributing and gpg install information.

Author: y3jo6

docs/contributing.md

@@ -6,12 +6,17 @@ When contributing to [commitizen](https://github.com/commitizen-tools/commitizen
 
 If you're a first-time contributor, you can check the issues with [good first issue](https://github.com/commitizen-tools/commitizen/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22) tag.
 
+## Install before contributing
+
+1. Install [poetry](https://python-poetry.org/), installation [pages](https://python-poetry.org/docs/#installing-with-the-official-installer)
+2. Install [gpg](https://gnupg.org), installation [pages](https://gnupg.org/documentation/manuals/gnupg/Installation.html#Installation). For Mac users, you could try [homebrew](https://brew.sh/).
+
 ## Before making a pull request
 
 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. Setup [pre-commit](https://pre-commit.com/) hook (`pre-commit install -t pre-commit -t pre-push -t commit-msg`)
+4. Setup [pre-commit](https://pre-commit.com/) hook (`poetry run pre-commit install -t pre-commit -t pre-push -t commit-msg`)
 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.)