title: Laravel 5.5 autodiscovery not registering
body: <p>I'm installing the <code>spatie\laravel-backup</code> package. According to the instructions, I just need to <code>composer require spatie\laravel-backup</code> and the package should be recognized and auto-installed. It looks like this is happening:</p>
  
  <pre><code>Generating optimized autoload files
  &gt; Illuminate\Foundation\ComposerScripts::postAutoloadDump
  &gt; @php artisan package:discover
  Discovered Package: spatie/laravel-backup
  </code></pre>
  
  <p>But looking in <code>/config/app.php</code> there's no mention of <code>backup</code> anywhere in the providers, and the expected <code>/config/backup.php</code> configuration file isn't found.</p>
  
  <p>Are there any additional commands I need to issue to complete the auto-discovery?</p>