title: Preloading, lazy loaded pages Ionic 4
body: <p>In Ionic 3 we had the option to preload pages by doing:</p>
  
  <pre><code>IonicModule.forRoot({
    preloadModules: true
  });
  </code></pre>
  
  <p>But when I try to do that in Ionic 4, it gives me an error:</p>
  
  <pre><code> Argument of type '{ preloadModules: boolean; }' is not assignable to parameter of type 'IonicConfig'.
  </code></pre>
  
  <p>Someones know how to do this in Ionic 4.</p>