updated README.md

## homepage

This code is available on *CSST GitLab*:

- [https://csst-tb.bao.ac.cn/code/csst-l1/csst_proto](https://csst-tb.bao.ac.cn/code/csst-l1/csst_proto).

[https://csst-tb.bao.ac.cn/code/csst-l1/csst_proto](https://csst-tb.bao.ac.cn/code/csst-l1/csst_proto).

## documentation

A sphinx-based documentation is available at

- [https://csst-proto.readthedocs.io/en/latest/](https://csst-proto.readthedocs.io/en/latest/)

## installation

| `requirements.txt` | code requirements               | √      | √   |     |

| `setup.py`         | sphinx-based documentation      | √√     | √   |     |

## important stages

1. **installation**: `source code` & `setup.py` -> `pip install <package_name>`

2. **a simple guide**: `README.md`

3. **unittest**: `pytest`

4. gitlab CI/CD pipeline: `.gitlab-ci.yml`

5. sphinx-based documentation: `doc/` & `readthedocs.yml`

## necessary skills

- git: https://git-scm.com/

  - Pro Git: https://git-scm.com/book/en/v2

- Numpydoc: https://numpydoc.readthedocs.io/en/latest/format.html

  - for C: https://peps.python.org/pep-0007/

  - for Python: https://peps.python.org/pep-0008/

- unittest: https://docs.python.org/3.8/library/unittest.html

- sphinx: https://www.sphinx-doc.org/en/master/index.html

- restructured text: https://docutils.sourceforge.io/rst.html

- readthedoc: https://readthedocs.io/ or https://rtfd.io/

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