doc/forums: Update Matrix channel link

Channel portalling has been disabled for the matrix.org-libera.chat
bridge[1]. Hence, we created a new Matrix channel #coreboot:matrix.org
(that is plumbed to the IRC channel).

[1] https://libera.chat/news/matrix-deportalling

Change-Id: I896bfed71790988503dc8229fe9b34e175046dbf
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/76864
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Patrick Georgi <patrick@coreboot.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/Documentation/community/forums.md b/Documentation/community/forums.md
index 14c108a..e334edc 100644
--- a/Documentation/community/forums.md
+++ b/Documentation/community/forums.md
@@ -14,7 +14,7 @@
 ## Real time chat
 
 We also have a real time chat room on [IRC](ircs://irc.libera.chat/#coreboot),
-also bridged to [Matrix](https://matrix.to/#/#coreboot:libera.chat) and a
+also bridged to [Matrix](https://matrix.to/#/#coreboot:matrix.org) and a
 [Discord](https://discord.gg/JqT8NM5Zbg) presence. You can also find us on
 [OSF Slack](https://osfw.slack.com/), which has channels on many open source
 firmware related topics. Slack requires that people come from specific domains