documentation: Update #nouveau IRC channel network

Like many free software projects, Nouveau recently moved from Freenode
to OFTC. Update the reference.

v3: Add acks.
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210725150007.2818-1-alyssa@rosenzweig.io

Documentation/driver-api/thermal/nouveau_thermal.rst

@@ -90,7 +90,7 @@ Bug reports
 -----------
 
 Thermal management on Nouveau is new and may not work on all cards. If you have
-inquiries, please ping mupuf on IRC (#nouveau, freenode).
+inquiries, please ping mupuf on IRC (#nouveau, OFTC).
 
 Bug reports should be filled on Freedesktop's bug tracker. Please follow
 https://nouveau.freedesktop.org/wiki/Bugs