[Task] Update docstrings for the public API

[Apricot-S]

Summary

Create a checklist of all public API elements and update their docstrings according to the style chosen in #120.

Scope

• Choose a unified docstring style for the project -> reST
  • Candidates: Google, NumPy, reST
  • Note: some existing docstrings already use reST
• Set [tool.ruff.lint.pydocstyle]
• Update docstrings to follow the unified style

[Apricot-S]

Before creating docstrings for other parts, it is probably a good idea to first create docstrings for 136-encoded tiles and 34-encoded tiles.
The explanation for each method can be made more concise by linking to the tile explanation.

I think the docstring for the mahjong/tile.py module should be the best place to explain this.

[Apricot-S]

I removed the list from the issue because we can track docstring additions with a linter.