add dnn to blocked sites for procrastination stopper

nixos/configuration.nix

@@ -204,6 +204,8 @@ in
         ::1   tagesschau.de
         127.0.0.1   tagesschau.de
         ::1   dnn.de
+        127.0.0.1   www.dnn.de
+        ::1   www.dnn.de
         127.0.0.1   dnn.de
         ''} /etc/hosts
     '';