(potential) short outage on Fedora Copr stack

[Pavel Raiskup]

To make the future outages much shorter, we need to flip our production
stack to a new set of IPs, which will require us to change DNS records.

This action shouldn't cause any outage in ideal case, but potentially
we'll have to reboot some services (outage shorter than 3 minutes, e.g.).

We'll do it tomorrow, 2020-11-12 around 10:00 CET.

Pavel