Update deprecation solution in Wiki: entity_get[_form]_display

[anotherjames]

Since https://www.drupal.org/node/2367933 / https://git.drupalcode.org/project/drupal/commit/da94d7fc6b6cd06a26c065ab8db640e9a0bb8671#7f7e72269405002d6602cb72b6155307148e699d_523_487 , the deprecation solution for usage of entity_get_display() and entity_get_form_display() have changed. The solutions should now be:

\Drupal::service('entity_display.repository')
  ->getViewDisplay($entity_type, $bundle, $view_mode);

and

\Drupal::service('entity_display.repository')
  ->getFormDisplay($entity_type, $bundle, $form_mode);

This ensures a valid display is returned even when it doesn't yet exist as saved configuration, just as entity_get_display() and entity_get_form_display() did.