This reverts commit 095fe5b43def40279a243e663c662b02caac5318. Pointless renames considered harmful. All they do is force people to spend extra work updating their configs for no benefit, and hindering the ability to switch between unstable and stable versions of NixOS. Like, what was the value of having the "nixos." there? I mean, by definition anything in a NixOS module has something to do with NixOS...
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.