Better support complex themes

A couple ideas for more complex themes:

  • Add a theme documentation page, accessible through the Ghost admin portal.
  • Add the ability for a theme to create posts/pages/tags. (For themes that rely on the existence of a specific page, or use a specific tag to create special functionality.)
  • Allow a theme to install a custom routes.yaml?

Use case: I’m building a theme that is probably not self-explanatory. Making it easier for the person trying the theme to get it set up would be nice!