nixos-option: Include manual page in the package

pkgs/tools/nix/nixos-option/default.nix

@@ -1,14 +1,33 @@
-{ lib, stdenv, boost, cmake, pkg-config, nix }:
+{ lib
+, stdenv
+, boost
+, cmake
+, pkg-config
+, installShellFiles
+, nix
+}:
 
 stdenv.mkDerivation {
   name = "nixos-option";
 
   src = ./.;
+  postInstall = ''
+    installManPage ${./nixos-option.8}
+  '';
 
   strictDeps = true;
-  nativeBuildInputs = [ cmake pkg-config ];
-  buildInputs = [ boost nix ];
-  cmakeFlags = [ "-DNIX_DEV_INCLUDEPATH=${nix.dev}/include/nix" ];
+  nativeBuildInputs = [
+    cmake
+    pkg-config
+    installShellFiles
+  ];
+  buildInputs = [
+    boost
+    nix
+  ];
+  cmakeFlags = [
+    "-DNIX_DEV_INCLUDEPATH=${nix.dev}/include/nix"
+  ];
 
   meta = with lib; {
     license = licenses.lgpl2Plus;