Hints for kruler in main

Hints

• asv-content-rating-missing
  org.kde.kruler.appdata.xml -
  This component has no `content_rating` tag to provide age rating information. You can generate the tag data online by answering a few questions at https://hughsie.github.io/oars/
• screenshot-no-thumbnails
  No thumbnails have been generated for screenshot 'https://cdn.kde.org/screenshots/kruler/kruler.png'.
  This could mean that the original provided screenshot is too small to generate thumbnails from.