This will be a book example https://git.door43.org/Door43/en-obs/pulls/8

Note: if we implement #42 we may deprecate the image audio and video container types.

@jag3773 after reviewing this I think we can safely deprecate the image, audio, and video container types now for a number of reasons.

1. we no longer need a container type to determine what format of content is provided. e.g. We either use the format field in the manifest or, if we follow through with Remove format definition from RC manifest #42, the file extension. This information is given it the catalog like "format":"application/zip; type=audio content=audio/mp3 conformsto=rc0.2".
2. These types are already structured like the book type anyway.
3. If we follow through with Remove format definition from RC manifest #42 this would open up the possibility of providing media for any container type.

@neutrinog Sounds good.

I removed the audio, video, and image types.