Include "Join via Matrix" info on the lobby landing page
Hi. I'm staring at https://gitter.im/VSCodium/Lobby from an un-authenticated window.
I know I can join from Matrix, but I can't remember how, and I know each time I do this, I wind up looking up the initial Matrix<->Gitter announcement to remember how to join via Matrix.
It might be nice if "Sign in to start talking" had another button next to it, "Join via Matrix" that linked to to the appropriate matrix.to link for that repo/room.
