conversions were done using https://github.com/pennae/nix-doc-munge
using (probably) rev f34e145 running
nix-doc-munge nixos/**/*.nix
nix-doc-munge --import nixos/**/*.nix
the tool ensures that only changes that could affect the generated
manual *but don't* are committed, other changes require manual review
and are discarded.
This module obsoletes services.gnome3.gnome-terminal-server
as that's a confusing option for users, and sounds internal.
It's much simpler to have a gnome-terminal module.
