Notify about bigger issues

Currently, if Traefik was automatically restarted within the last 10 hours and is then detected to be down again, the Watchdog simply does nothing.

Maybe it should notify someone somehow. But: Via mail? The ticket system will also be down. Maybe we should mail Gruppe Technik, or notify someone via chat? Or send a mail to someones personal address?

And: The cronjob runs every 3 minutes. We should ensure that this mail isn't sent more than once (or a few times).