Restructure machine files

machines/default.nix

@@ -1,11 +1,11 @@
 {
   sue = {
     system = "x86_64-linux";
-    module = import ./sue;
+    nixosModule = import ./sue/configuration.nix;
   };
 
   gamepc = {
     system = "x86_64-linux";
-    module = import ./gamepc;
+    nixosModule = import ./gamepc/configuration.nix;
   };
 }