Add patience parameter for early_stopping (or at least make it clear that patience=20 by default)

[codeananda]

The current docs are not clear what the default patience is for early stopping. They don't mention it in the docstring for fit.

# fit docstring
early_stopping : bool
    Flag whether to use early stopping to stop training when training / validation loss is no longer improving.

It's only in utils.configure_trainer that we see the default patience value

    if early_stopping:
        if not metrics_enabled:
            raise ValueError("Early stopping requires metrics to be enabled.")
        if not has_earlystopping_callback:
            early_stop_callback = pl.callbacks.EarlyStopping(
                monitor=early_stopping_target, mode="min", patience=20, divergence_threshold=5.0
            )
            callbacks.append(early_stop_callback)

Suggested improvements

1. Change docstring to mention default patience
2. Add a patience param to fit