[fix] matrixrooms add proper MRS integration

Related:

- https://github.com/searxng/searxng/issues/2918

searx/settings.yml

@@ -1043,10 +1043,12 @@ engines:
     base_url: https://mastodon.social
     shortcut: mah
 
-  - name: matrixrooms
-    engine: matrixrooms
-    shortcut: mtrx
-    disabled: true
+  # - name: matrixrooms
+  #   engine: mrs
+  #   # https://docs.searxng.org/dev/engines/online/mrs.html
+  #   # base_url: https://mrs-api-host
+  #   shortcut: mtrx
+  #   disabled: true
 
   - name: metacpan
     engine: metacpan