/**
 * Implements hook_link_alter().
 */
function {{ machine_name }}_link_alter(&$variables) {
  // Add a warning to the end of route links to the admin section.
  if (isset($variables['route_name']) && strpos($variables['route_name'], 'admin') !== FALSE) {
    $variables['text'] = t('@text (Warning!)', ['@text' => $variables['text']]);
  }
}