[Mne_analysis] Possibility of adding public dataset - BCI Competition IV

[Alexandre Gramfort]

        External Email - Use Caution        

> Sorry for the late response, thanks Clemens and Alex by the useful information. In order to not re-manufacture the wheel, I think the best option would be to leave the default BCI dataset in MNE and in the documentation refer to MOABB for more dataset options. What do you think? I can make the necessary modifications in a PR.

+1 to point to MOABB in the relevant MNE-Python doc.

thanks
Alex