docs: Include generated supported provided files.

This is needed, because we can't run pre documentation build step on RTD.
docs: Remove wip notice, move other notice to the bottom of the page (we don't
want to scare new users off).
docs: fix underline.
Re-apply previously reverted patch, regenerate documentation fixtures.
Don't include dummy providers in the provider table.
docs: re-generate fixtures.
docs: Update upgrade notes.