Reformat doc section relative to OOD methods

[y-prudent]

OOD methods documentation: https://deel-ai.github.io/oodeel/api/methods/

The API documentation of OOD methods is messy and difficult to read. Some suggestions:

• Do not display irrelevant private methods.
• Find a way to make the fit method appear in the docstring. It would also be nice to have a personalized fit docstring per method.
• Create one markdown page per method to add some examples and guidelines.