modules/profiles/minimal: sound is disabled by default

The option is `false` by default since
e349ccc77f, so we don’t need to mention
it explicitely in these minimal configs.

nixos/modules/profiles/headless.nix

@@ -6,7 +6,6 @@
 with lib;
 
 {
-  sound.enable = false;
   boot.vesa = false;
 
   # Don't start a tty on the serial consoles.

nixos/modules/profiles/minimal.nix

@@ -13,5 +13,5 @@ with lib;
 
   documentation.enable = mkDefault false;
 
-  sound.enable = mkDefault false;
+  services.nixosManual.enable = mkDefault false;
 }

nixos/modules/virtualisation/container-config.nix

@@ -7,7 +7,6 @@ with lib;
   config = mkIf config.boot.isContainer {
 
     # Disable some features that are not useful in a container.
-    sound.enable = mkDefault false;
     services.udisks2.enable = mkDefault false;
     powerManagement.enable = mkDefault false;