GitLab

I added ToC for docs v1 & started setting up for doc-builder. cc @Narsil
@osanseviero

---------
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
Co-authored-by: osanseviero <osanseviero@gmail.com>
Co-authored-by: Mishig <mishig.davaadorj@coloradocollege.edu>