[gimp-web] content: update discuss page with Matrix bridge and pixls.us.

[Jehan <jehanp src gnome org>]

commit 4fc7a2efb35d3928762988d6cf8f4b25e266e9d9
Author: Jehan <jehan girinstud io>
Date:   Wed Dec 22 15:33:59 2021 +0100

    content: update discuss page with Matrix bridge and pixls.us.
    
    - Add Matrix bridges for all IRC channels.
    - Add pixls.us as a managed forum.
    - Improve a bit Discord description.

 content/about/discuss.md | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)
---
diff --git a/content/about/discuss.md b/content/about/discuss.md
index 131a53d5..d4ecd2d4 100644
--- a/content/about/discuss.md
+++ b/content/about/discuss.md
@@ -24,21 +24,22 @@ outside of our control. Other discussions channels are not necessarily
 centrally archived, yet many users store every discussion happening.
 Don't send any private or sensitive information! ⚠️
 
-## IRC
+## IRC / Matrix
 
 The official GIMP IRC channels are on GIMPNet
 ([irc.gimp.org](irc://irc.gimp.org/)) and have existed for more than 20
 years. Many [channels related to GTK+ and
 GNOME](https://live.gnome.org/GnomeIrcChannels) are also on GIMPNet.
+Matrix bridges are available.
 
-irc://irc.gimp.org/[#gimp-users](irc://irc.gimp.org/gimp-users)
+irc://irc.gimp.org/[#gimp-users](irc://irc.gimp.org/gimp-users) (alt: [Matrix 
bridge](https://matrix.to/#/#gimp:gnome.org))
 : Main support channel for GIMP users.
 
-irc://irc.gimp.org/[#gimp](irc://irc.gimp.org/gimp)
+irc://irc.gimp.org/[#gimp](irc://irc.gimp.org/gimp) (alt: [Matrix 
bridge](https://matrix.to/#/#gimp-users:gnome.org))
 : Original channel, created in early 1997 for users and developers.
 Discussions often focus on GIMP development.
 
-irc://irc.gimp.org/[#gimp-web](irc://irc.gimp.org/gimp-web)
+irc://irc.gimp.org/[#gimp-web](irc://irc.gimp.org/gimp-web) (alt: [Matrix 
bridge](https://matrix.to/#/#gimp-web:gnome.org))
 : Channel devoted to this web site and related GIMP sites.
 
 ## Mailing Lists
@@ -86,9 +87,15 @@ works.<br/>
 Old Archives:
 [mail-archive](https://www.mail-archive.com/gimp-docs%40lists.xcf.berkeley.edu/)*
 
+## Forum
+
+A [forum to discuss GIMP topics](https://discuss.pixls.us/gimp/) is
+hosted at *pixls.us*, the community for Free/Open Source Photography.
+
 ## Discord
 
-A [Discord server](https://discord.gg/W28dWtku2W) is also available.
+A [Discord server](https://discord.gg/W28dWtku2W) (another real-time
+(chat) discussion channel) is also available.
 
 ## Code of Conduct