Proper examples for deep methods

[tgnassou]

We need to provide way better example of the deep methods. For each methods we should provide a training example (which is already done) and then an explanation of what is happening:

• adversarial method -> domain prediction
• divergence methods and OT methods -> TSNE of the features

We should also explain how to train the methods with skorch or torch. That is already what I started to do in plot_training_method.py.