Improve documentation of the list of supported models

[ThomasBouche]

We've noted this in the readme:
"Shapash works for Regression, Binary Classification or Multiclass problem.
It is compatible with many models: Catboost, Xgboost, LightGBM, Sklearn Ensemble, Linear models, SVM."

But we'll have to see to it that it's more obvious in the various documentations.
And also specify that these contributions can be calculated and added to the smartexplainer