Update the link to F-List to point to the current repository

Testing Done:
Ran locally.

Bugs closed: NEST-40

Reviewed at
title: Gadu-Gadu
date: 2019-06-12T02:23:48.000Z
weight: 20
lastmod: 2019-08-22T04:47:10.000Z
### What is Gadu-Gadu?
Gadu-Gadu is an IM protocol popular in Poland. You can find more about it
[here]( (website in Polish).
### I compiled Pidgin from source. Why doesn't it have Gadu-Gadu support?
We use an external libgadu. Install your distro's `libgadu-dev` (Debian-based
systems) or `libgadu-devel` (RPM systems) and rebuild Pidgin (making sure to
re-run `./configure` in the top of the source tree).