nixos/tools: add networkmanager to configuration template

nixos/modules/installer/tools/tools.nix

@@ -133,7 +133,9 @@ in
 
       $bootLoaderConfig
         # networking.hostName = "nixos"; # Define your hostname.
+        # Pick only one of the below networking options.
         # networking.wireless.enable = true;  # Enables wireless support via wpa_supplicant.
+        # networking.networkmanager.enable = true;  # Easiest to use and most distros use this by default.
 
         # Set your time zone.
         # time.timeZone = "Europe/Amsterdam";