201f9beddb
The rationale for disabling this is: 1) systemd timers are better; 2) it gets rid of one usually unnecessary process, which makes containers more light-weight. Note that cron is still enabled if services.cron.systemCronJobs is non-empty, so this only matters if you have no declarative cron jobs but do have user cron jobs.
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.