MRG: Improve DICS example (#6305)
MRG: Improve DICS example (#6305)

* Improve DICS example

The old DICS example was done on the mne-sample dataset, but DICS is
demonstrated better on data that has clear oscillatory activity. This PR
changes the example to apply DICS to the "somato" data to localize the
ERS in the beta band.

* Fix picks

* Fix spelling

wmvanvliet/mne-python,adykstra/mne-python,adykstra/mne-python,drammock/mne-python,olafhauk/mne-python,pravsripad/mne-python,Teekuningas/mne-python,drammock/mne-python,drammock/mne-python,Teekuningas/mne-python,kambysese/mne-python,kambysese/mne-python,wmvanvliet/mne-python,larsoner/mne-python,mne-tools/mne-python,wmvanvliet/mne-python,bloyl/mne-python,olafhauk/mne-python,olafhauk/mne-python,kingjr/mne-python,bloyl/mne-python,rkmaddox/mne-python,Teekuningas/mne-python,pravsripad/mne-python,larsoner/mne-python,mne-tools/mne-python,kingjr/mne-python,kingjr/mne-python,cjayb/mne-python,Eric89GXL/mne-python,rkmaddox/mne-python,pravsripad/mne-python,Eric89GXL/mne-python,cjayb/mne-python,larsoner/mne-python,mne-tools/mne-python