nixos-module/network: try to make resolv.conf more compatible

nix/nixos-module/network.nix

@@ -60,6 +60,7 @@ in
   networking.useHostResolvConf = false;
   services.resolved.enable = false;
   environment.etc."resolv.conf".text = ''
-    nameserver 172.20.73.8 9.9.9.9
+    nameserver 172.20.73.8
+    nameserver 9.9.9.9
   '';
 }