Eelco Dolstra d4636fa254 Revert "Add a way to pin a NixOS version within the module system."
This reverts commit a5992ad61b314104aff7e28a41ce101a1b0e7c35. Motivation:

a5992ad61b (commitcomment-14986820)
2016-02-27 20:48:12 +01:00
..
2015-12-10 19:17:33 +01:00
2015-12-26 12:36:19 -06:00
2014-07-23 15:00:25 +02:00
2014-08-25 19:08:31 +02:00

To build the manual, you need Nix installed on your system (no need
for NixOS). To install Nix, follow the instructions at

    https://nixos.org/nix/download.html

When you have Nix on your system, in the root directory of the project
(i.e., `nixpkgs`), run:

    nix-build nixos/release.nix -A manual.x86_64-linux

When this command successfully finishes, it will tell you where the
manual got generated.