Fixed bad option in it-tools, pi-hole and traefik. Added virtualization file.

modules/services/virtualization.nix

@@ -0,0 +1,15 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.numbus.services.virtualization;
+in
+
+{
+  options.numbus.services.virtualization = {
+    enable = mkEnableOption "QEMU/KVM virtualization software";
+  };
+
+  config = mkIf cfg.enable {
+    virtualisation.libvirtd.enable = true;
+  };
+}