I hate the thing too even though I made it, and rather just get rid of it. But we can't do that yet. In the meantime, this brings us more inline with autoconf and will make it slightly easier for me to write a pkg-config wrapper, which we need.
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.