fe744d3fb1
Because when I see "config.system.build.manual.manual" after I forgot what it means I ask "Why do I need that second `.manual` there again?". Doesn't happen with `config.system.build.manual.manualHTML`.
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.