This mirrors the behaviour of systemd - It's udev that parses `.link` files, not `systemd-networkd`. This was originally applied in36ef112a47, but was reverted due to1115959a8dcausing evaluation errors on hydra.
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.