Add a hookable method to define additional URLs for each page included in the sitemap apart from its actual URL.

Mainly useful for adding dynamic URL segments:

• https://example.web/artists/some-artist/ (included)
• https://example.web/de/kuenstler/ein-kuenstler/ (included)
• https://example.web/artists/some-artist/gallery/ (URL segment added via hook)
• https://example.web/de/kuenstler/ein-kuenstler/galerie/ (URL segment added via hook)

Example hook:

wire()->addHookAfter('MarkupSitemap::getAdditionalPageUrls', function ($event) {
  $page = $event->arguments(0);
  $language = $event->arguments(1);

  if ($page->template == 'artist') {
    $urls = [
      // Gallery sub-page
      'gallery' => [
        'url' => $page->httpUrl([
            'language' => $language,
            'urlSegmentStr' => _x('gallery', 'Slug'),
        ]),
        'modified' => $page->images->first->modified,
      ],
      // Profile sub-page
      'profile' => [
        'url' => $page->httpUrl([
            'language' => $language,
            'urlSegmentStr' => _x('profile', 'Slug'),
        ]),
        'priority' => 0.2,
      ],
    ];
  }

  $event->return = $urls;
});