Since commits 89e9837 and 5b8dae8 the manual no longer depends on evaluation of any packages from nixpkgs, so all errors of the form "Package 'foo' is not supported on 'armv7l-linux'" are gone.
*** 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.