Use defaultPackage as ngnix document root

flake.nix

@@ -28,7 +28,7 @@
           ];
         };
       })) // {
-        nixosModule = { config, ... }: {
+        nixosModule = { config, pkgs, ... }: {
           services.nginx = {
             enable = true;
 
@@ -36,7 +36,7 @@
               enableACME = true;
               forceSSL = true;
 
-              root = "/srv/www/erambler.co.uk";
+              root = self.defaultPackage.${pkgs.system};
             };
           };