disabled man cache

it takes forever to generate

config/common/default.nix

@@ -36,6 +36,7 @@ with lib; {
 
   security.dhparams.defaultBitSize = 4096;
 
+  documentation.man.generateCaches = false;
   system.activationScripts.motd.text = let
     cfg = config.system.nixos;
   in ''

config/profiles/headless.nix

@@ -2,7 +2,6 @@
 
   kyouma.machine-type.headless = true;
 
-  documentation.man.generateCaches = false;
   environment.systemPackages = with pkgs; [
     vim
   ];