Enhance documentation

[EarlMilktea]

Mentioned in #223 :

• [ ] Add a helpful section for configuring vscode settings to check for things on editor
• [ ] Add a section for local checks guide (in addition to PR template): nox, ruff, any other?

My suggestions:

• [ ] Add doctest
• [ ] Coherently use numpy style for docstrings
• [ ] Use hyperlinks in the documentation for better maintenability

[shinich1]

note: first items to be added in contributing guide (both on main repo and in doc)

[EarlMilktea]

@shinich1 Let me partly work on this after #228 (only for basic modules already refactored)