Clarify readme and contributing documentation (#105, #155)

• Fix documentation link
• Improve first installation step
• Remove black §, covered into pre-commit §
• Merge contributing from readme into contributing.md
• readme: Remove need for Poetry to run examples
• readme: Add missing requirements

Close #105 (closed), #155 (closed).

CONTRIBUTING.md

 # Contribute guide
 
+## Install development environment
+
+- [Install Poetry](https://python-poetry.org/docs/#installation)
+- Install DuniterPy runtime and dev (test) dependencies:
+
+```bash
+poetry install
+```
+
 ## Development workflow
 
 Create and push a feature or bugfix release out of the `main` branch.
@@ -63,18 +72,6 @@ set -xg GITLAB_PRIVATE_TOKEN ""
 
 Check out #169 for more details.
 
-### Black formatting
-
-We are using [Black](https://github.com/psf/black) formatter tool.
-Run Black on a Python file to format it:
-
-```bash
-poetry run black duniterpy/file.py
-```
-
-With `pre-commit`, Black is called on staged files, so the commit should fail in case black would make changes.
-You will have to add Black changes in order to commit your changes.
-
 ## Tests
 
 We are using [`pytest` framework](https://docs.pytest.org/).
@@ -102,6 +99,38 @@ duniterpy> poetry run pytest tests/helpers/test_ws2p.py::test_generate_ws2p_endp
 Follow [this documentation](https://github.com/Lucas-C/pre-commit-hooks#removing-old-license-and-replacing-it-with-a-new-one)
 Only difference is to update the year in `license_header.txt` rather than `LICENSE.txt`.
 
+## Manual packaging and deployment to PyPI test and PyPI repositories
+
+Change and commit and tag the new version number (semantic version number)
+
+```bash
+./release.sh 1.2.0
+```
+
+Build the PyPI package in the `dist` folder
+
+```bash
+make build
+```
+
+Deploy the package to PyPI test repository:
+
+```bash
+make deploy_test
+```
+
+Install DuniterPy from PyPI test repository and its dependencies from PyPI:
+
+```bash
+pip install --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.python.org/simple/ duniterpy
+```
+
+Deploy the package on PyPI repository:
+
+```bash
+make deploy
+```
+
 ## Release workflow
 
 To handle a release, you have to follow this workflow:
@@ -118,3 +147,21 @@ To handle a release, you have to follow this workflow:
 - Create a MR containing the changelog and the commit updating the version
 - Once the MR is merged to `main`, push the tag with `git push --tags`
 - To release to PyPI, the pipeline based on the tag should be used by triggerring the manual job on the `main` branch
+
+### How to generate and read locally the autodoc
+
+- Install Sphinx, included into the `doc` dependencies group:
+
+```bash
+poetry install --with doc
+```
+
+- Generate HTML documentation in `public` directory:
+
+```bash
+make docs
+```
+
+## Docstrings
+
+- When writing docstrings, use the reStructuredText format recommended by https://www.python.org/dev/peps/pep-0287/#docstring-significant-features