Description of the problem

The API doc Shows that the default value for parameter exclude is 'bads', but in the description for that parameter, it says that the default is None, when In fact, None is not even a valid argument for this parameter:

exclude : None | list of str | 'bads'
   Channels names to exclude from being shown. If ``'bads'``, the
  bad channels are excluded. Defaults to ``None``.

Steps to reproduce

sample_fpath = mne.datasets.sample.data_path()
fpath = sample_fpath / "MEG" / "sample" / "sample_audvis_raw.fif"
raw = mne.io.read_raw(fpath, preload=True).pick("eeg")

epochs = mne.make_fixed_length_epochs(raw, duration=1, preload=True)
evoked = epochs.average()
evoked.plot_joint(exclude=None) # include/exclude must be list, tuple, ndarray, or "bads". You provided type <class 'NoneType'>.

Expected results

Figure shows with no bad channels excluded.

Actual results

ValueError: include/exclude must be list, tuple, ndarray, or "bads". You provided type <class 'NoneType'>.

Additional information

Should the code be fixed to match the docstring (i.e. accept None, and make it the default), or should the mention of None simply by removed from the docstring?