generify the vpn setup

modules/nixos/default.nix

@@ -1,6 +1,5 @@
 # Add your reusable NixOS modules to this directory, on their own file (https://nixos.wiki/wiki/Module).
 # These should be stuff you would like to share with others, not your personal configurations.
 {
-  # List your module files here
-  contabo.wan = import ./contabo/wan;
+  vpn-ip = import ./vpn-ip;
 }