Update Documentation

[sylvchev]

Documentation needs care. Apart from issue #46, I spotted some minor corrections to make:

• In API, SSVEPExo() appears in MI datasets which is not correct. It is also correctly listed in SSVEP datasets
• Paradigms in API list only Motor Imagery, no ERP nor SSVEP.

[Div12345]

I think the automatic update of the Sphinx Documentation is probably not working. Will look into maybe using something like this https://github.com/marketplace/actions/sphinx-build for ensuring that.

An example for using it - https://github.com/ammaraskar/sphinx-action-test

[Div12345]

Or an alternate would be using something like https://docs.readthedocs.io/en/stable/features.html

[sylvchev]

The documentation may be hosted on https://github.com/NeuroTechX/moabb.github.io repo. There is a CircleCI config item to automatically build the documentation and push it to the moabb.github.io page. It seems not to be working right now.
We may remove the CircleCI config file as it is not used right now, but it is still visible in the history. Like here: https://github.com/NeuroTechX/moabb/blob/55f77ae305e1f0960e781a57895cb34ad6af0c62/.circleci/config.yml