For many OS install scenarios, one runs through an installer which may
come with embedded data, and then the OS is configured post-install to
receive updates.
In this model, it'd be nice to avoid the post-install having to rewrite
the /ostree/repo/config file.
Additionally, it feels weird for admins to interact with "/ostree" -
let's make the system feel more like Unix and have our important
configuration in /etc.
https://bugzilla.gnome.org/show_bug.cgi?id=729343