BlockCreationTrait::placeBlock() should explain visibility

Working on this

  /**
   * Creates a block instance based on default settings.
   *
   * @param string $plugin_id
   *   The plugin ID of the block type for this block instance.
   * @param array $settings
   *   (optional) An associative array of settings for the block entity.
   *   Override the defaults by specifying the key and value in the array, for
   *   example:
   *   @code
   *     $this->drupalPlaceBlock('system_powered_by_block', array(
   *       'label' => t('Hello, world!'),
   *     ));
   *   @endcode
   *   The following defaults are provided:
   *   - label: Random string.
   *   - id: Random string.
   <del>*   - region: 'sidebar_first'.</del>
   *   - region: 'content'.
   *   - theme: The default theme.
   *   - visibility: Empty array (block will be visible on all pages).
   *
   * @return \Drupal\block\Entity\Block
   *   The block entity.
   *
   * @todo
   *   Add support for creating content block instances.
   */
  protected function placeBlock($plugin_id, array $settings = []) {
    $config = \Drupal::configFactory();
    $settings += [
      'plugin' => $plugin_id,
      'region' => 'content',
      'id' => $this->randomMachineName(8),
      'theme' => $config->get('system.theme')->get('default'),
      'label' => $this->randomMachineName(8),
      'visibility' => [],
      'weight' => 0,
    ];

@joachim looking at this, i found that the default value for region is

sidebar_first

, but in function definition its taking

content

as default region

+ will it be good idea to provide the example with few more settings like visibility, region, theme instead of just label.