Feature Request: Metadata settings within configuration->site or site.yaml

Via admin-plugin or directly in site.yaml you can predefine content for several metatags. This could be

metadata:
  description: 'My nonsense description.'
  keywords: lorem,ipsum
  author: Peter Test

If you create a page, you can override this information via options.

In my opinion it would be extremely useful, if the predefined metatags would already be implemented in options instead of the need to initially set them for overriding - including showing what content every metatag-item contains.

Thanks for checking and regarding this request.