community: Use IRC as community channel

Bug: https://git.ostc-eu.org/distro/docs/-/issues/86
Forwarded: https://booting.oniroproject.org/distro/docs/-/merge_requests/216
Relate-to: https://git.ostc-eu.org/distro/docs/-/merge_requests/211
Relate-to: https://booting.oniroproject.org/distro/docs/-/merge_requests/211


Thanks-to: Nawab Ahmad Reshi
Signed-off-by: Philippe Coval <philippe.coval@huawei.com>