System messages trigger notifications when user is mentioned (#3235)

i18n/en.json

@@ -47,6 +47,10 @@
     "id": "September",
     "translation": "September"
   },
+  {
+    "id": "system.message.name",
+    "translation": "System"
+  },
   {
     "id": "api.general.init.debug",
     "translation": "Initializing general api routes"