Fix typo

Author: andyondrya

core/config_help.json

@@ -227,7 +227,7 @@
     "default": "Yes",
     "description": "This is the channel where update notifications are sent to.",
     "examples": [
-      "`{prefix}config set update_notifications no"
+      "`{prefix}config set update_notifications no`"
     ],
     "notes": [
       "This has no effect unless `disable_autoupdates` is set to no.",