The "trusted host" warning on the status report links to https://www.drupal.org/node/1992030, which is a handbook page that is also aliased as https://www.drupal.org/docs/8/install/trusted-host-settings.
Linking to aliases is better than hard-coded node IDs, both because the URL looks nicer and because it is more future-proof (see #2914292: Remove hard coded reference to node/2179269).