Feature request: detect Private DNS

A feature I like in Intra is that it shows that Private DNS is enabled and that it's not necessary to enable Intra. It would be nice if Nebulo could do something similar as currently the lock is unlocked when it's disabled and there is no hint that due to private DNS there is protection.

Maybe this would also be a good place to explain why one might want to enable Nebulo instead of the integrated functionality or even a suggestion to enable both and if it's possible to link to private DNS settings even if the user had MiUi which hides the option.

Potentially related: #105