MRG: Display averaged time period in Evoked topomap title

[hoechenberger]

Also improve the documentation and mention that the time windows for averaging actually get clipped at the "ends" of the data.

main	this PR

# %%
from pathlib import Path
import mne


sample_dir = Path(mne.datasets.sample.data_path())
sample_fname = sample_dir / 'MEG' / 'sample' / 'sample_audvis_raw.fif'

raw = mne.io.read_raw_fif(sample_fname)
raw.crop(tmax=60)

events = mne.find_events(raw, stim_channel='STI 014')
event_id = {'auditory/left': 1, 'auditory/right': 2, 'visual/left': 3,
            'visual/right': 4, 'face': 5, 'buttonpress': 32}

epochs = mne.Epochs(raw, events=events, event_id=event_id,
                    tmin=-0.2, tmax=0.5, baseline=(None, 0),
                    preload=True)

evoked = epochs.average()
evoked.plot_topomap(average=0.1);
evoked.plot_joint(topomap_args=dict(average=0.1));

[sappelhoff]

nice 👍

[hoechenberger]

@larsoner please merge if happy

[larsoner]

Thanks @hoechenberger !