Now the private content is stored as a git submodule.
This means I can keep that repo's source private, but still use it in
the build product.
The build product (website) relies on HTTP basic authentication, so
access control is maintained throughout the SDLC.
Previously this repo used nix and nginx to manage deployment. All of
that happens in another repo (nixos-config) to manage virtual hosts. Now
this repo's deployment stage just pushes content.
