Error in Quick Start guide

[Valentin-Laurent]

Is your documentation request related to a problem? Please describe.
There is an error in the Quick Start guide, section 2 (Run MAPIE regressor):

MAPIE returns a np.ndarray of shape (n_samples, 3, len(alpha)) giving the predictions, as well as the lower and upper bounds of the prediction intervals for the target quantile for each desired alpha value.

Describe the solution you'd like
Suggested correction:

MAPIE returns a tuple, the first element is a np.ndarray of shape (n_samples) giving the predictions, and the second element a np.ndarray of shape (n_samples, 2, len(alpha)) giving the lower and upper bounds of the prediction intervals for the target quantile for each desired alpha value.

Also, clarifying the signification of "pis" (predictions interval s?) in y_pis may be a good idea.