Stop deploying docs

[nissy-dev]

When I searched by "deepchem docs", I hitted old docs (deepchem.io/docs).

I think it is not good for many users,
so we should remove docs files in this repo and stop deploying.

[rbharath]

Good point! We should stop deploying the docs and set up a redirect so deepchem.io/docs -> deepchem.readthedocs.io.