readme: move the support channel on libera
This lingered a bit but the Freenode situation is becoming clownier and clownier by the hour.
--HG-- branch : stable
This instance will be upgraded to Heptapod 18.5.1 on 2025-11-13 between 17:00 and 18:00 UTC+2
This lingered a bit but the Freenode situation is becoming clownier and clownier by the hour.
--HG-- branch : stable