Due to the recent changes at Freenode and the recommendation from the
X.Org board of moving to OFTC[1], many mesa-developers have moved over
to the #dri-devel channel on OFTC by now.

So let's promote that channel rather than the Freenode channel.

While we're at it, let's correct[2] the URI to use a slash to separate
between the host and channel. And omit the # from the channel name for
maximum compatibility.

[1]: https://lists.freedesktop.org/archives/mesa-dev/2021-May/225271.html
[2]: https://en.wikipedia.org/wiki/Internet_Relay_Chat#URI_scheme



Reviewed-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <!10917>