Merge pull request #2723 from prometheus/nexucis/remove-matrix-url

remove matrix url as it is abandoned

Author: sysadmind

src/app/community/community.md

@@ -20,10 +20,6 @@ use to communicate and contribute:
 
 `#prometheus` on [irc.libera.chat](https://libera.chat/).
 
-### Matrix
-
-[`#prometheus:matrix.org`](https://app.element.io/#/room/#prometheus:matrix.org).
-
 ### User mailing lists
 
 - [prometheus-announce](https://groups.google.com/forum/#!forum/prometheus-announce) ([mirror](https://www.mail-archive.com/[email protected]/))