Added warnings for previous gitbook users (#7945)
Added warnings for previous gitbook users (#7945)

Close https://github.com/readthedocs/readthedocs.org/issues/7939

Co-authored-by: Santos Gallegos <c93ded90b46be7383e4bbe2bf57d9211ae19c2eb@protonmail.com>
rtfd/readthedocs.org,rtfd/readthedocs.org,rtfd/readthedocs.org,rtfd/readthedocs.org