Feature/sg 1070 Remove description property -> include it in update instead + add docstrings

[Louis-Dupont]

Main Change

Storing the title, description, notice and warnings inside the output of each feature instead of handling it like an internal state (with properties)

Why ?

• Simplifies the overall code. The state based approach was
  • Error prone (risk of forgetting to update the state and the description)
  • Harder to navigate through the code, and less intuitive
  • Kind of spaghetti code
  • This without any clear benefit

Other

1. Adding more detailed docstrings for feature extractors

Why ?

• Well this is always good to have (most classes didnt have any clear docstring)
• Since the description property is removed, we cannot use it anymore to generate the documentation. The workaround (and probably cleaner approach anyway) is to generate the description of the feature based on the feature docstring
  • Eventually, when we will add mkdocs we won't need the documentation script anymore, but then with this PR will already have proper docstrings for each feature so it's still a win

2. Including Classification to the auto-generated documentation

[BloodAxe]

Let's change the name of PR title to a friendlier explanation (Then it is easier for github to compose release notes)

[BloodAxe]

LGTM