Resolve "Provide license information for images"

Feature

Summary

This MR provides…

• a draft for representing license information for images

Use Cases

As an application serving images with the TextAPI, I can be legally bound to provide a license for an image and information about the image's creator.

Plus, without a license the images aren't re-usable.

Are there parts of the documentation we have to adjust

• Yes, and I already did!

Changelog

• I added a statement to the CHANGELOG.

Related Tickets

Closes #14 (closed).

Logs and Screenshots

/cc Mathias Göbel, Frank Schneider, Michelle Weidling