e826a6ce03
Specifying mailboxes as a list isn't a good approach since this makes it impossible to override values. For backwards-compatibility, it's still possible to declare a list of mailboxes, but a deprecation warning will be shown.
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.