[Development] Changes to Freenode's IRC

[lj p]

> On 20 May 2021, at 12:17 am, Giuseppe D'Angelo via Development <development at qt-project.org> wrote:
> [snip]

The chat channels are fragmented these days. There’s the Qt discord channels, QtMob on Slack, Qt and Advanced C++ on Telegram. Not to mention freenode ones, that no one uses anymore, or the internal Qt Company Teams. There are probably other ones I am not aware of.