Invalid syntax error on the calculate_add_metrics cell

[ludovicmoncla]

There is a syntax error in the following cell:

#EXAMPLE
my_classifier.calculate_add_metrics(a
    y_true=my_classifier.orig_label,
    y_pred=my_classifier.pred_label,
    y_score=my_classifier.pred_conf,
    phase="test",
)

found in this page: https://mapreader.readthedocs.io/en/latest/User-guide/Classify/Train.html#testing
The a must be removed after the parenthesis.

[rwood-97]

Will add to #417