index-main/site/config/menu.php

<?php

return [
  'home' => [
    'label'   => 'Dashboard',
    'icon'    => 'bolt',
    'link'    => '/',
    'current' => function (string $current): bool {
      $path = Kirby\Cms\App::instance()->path();
      return Str::contains($path, '/site');
    }
  ],
  '-',
  'users'
];