Astroquery.mast Documentation Fixes

Thomas Dutkiewicz pointed out to me that this method of authorization with the token parameter is deprecated:


Rather, the verification process is now bound to the `login` method, where you can still feed it a token and log into the system to get proprietary data:

The documentation will need to be updated accordingly

@bsipocz - we are planning to make a PR to consolidate a couple of documentation updates for `astroquery.mast` . Would it be possible to add @ttdutkiewicz as a contributor so I can tag him in PRs and assign him stuff?