Now that we've switched to ipfire geoip, invite relay operators to submit fixes

Now that we've merged the switch from maxmind to ipfire (#40224 (closed)), we will have some bumps where it gets the locations wrong for some relay operators. The good news is that we finally have a geoip db that wants to hear bug reports and corrections! So we should gather some instructions together for relay operators -- (a) how to look up their IP address to country mapping, and (b) how to submit a correction to ipfire if needed.

For how to look up, I think they can do it manually via
https://location.ipfire.org/lookup/128.31.0.34
And in the future (post tpo/metrics/relay-search#40004) relay-search should show the mapping too, but we're not there yet.

And for how to submit a correction:

• make an account on their bugzilla: https://people.ipfire.org/register
• file a ticket in https://bugzilla.ipfire.org/enter_bug.cgi?product=Location%20Database

It's probably smart to go through this process ourselves at least once to make sure that it works and to see if we find a way to streamline it further. :)