Hints for gnome-multi-writer in main

Hints

• asv-nonstandard-gnome-extension
  :593 - kudos
  This tag is a GNOME-specific extension to AppStream and not part of the official specification. Do not expect it to work in all implementations and in all software centers.
• asv-desktop-app-launchable-omitted
  -
  This `desktop-application` component has no `desktop-id` launchable tag, however it contains all the necessary information to display the application. The omission of the launchable entry means that this application can not be launched directly from installers or software centers. If this is intended, this information can be ignored, otherwise it is strongly recommended to add a launchable tag as well.
• asv-content-rating-missing
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  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/