🐛 Bug description

Missing links in the docs : https://pytorch.org/ignite/contrib/engines.html#module-ignite.contrib.engines.common for methods:

• add_early_stopping_by_val_score -> EarlyStopping
• gen_save_best_models_by_val_score -> Checkpoint
• save_best_model_by_val_score -> Checkpoint