add boilerplate

modules/default.nix

@@ -1,4 +1,10 @@
-{ self, inputs, ... }: {
+{
+  self,
+  inputs,
+  config,
+  ...
+}:
+{
   flake.nixosConfigurations.nerv = inputs.nixpkgs.lib.nixosSystem {
     modules = with self.nixosModules; [
       user
@@ -7,5 +13,6 @@
       boot
       /etc/nixos/hardware-configuration.nix
     ];
+    config.dualBoot = true;
   };
 }