The "document" format for page content isn't documented

Endpoints that return page content generally allow you to select either markdown or document formats. From what I can tell, the document format isn't actually documented anywhere, which limits its utility.

This is problematic in my case because the AI search sources refer to page sections by their keys. I can't get the key for a particular page section unless I get the doc back in document format. I want to be able to pull out the relevant sections from an AI search response and feed them back into an LLM, formatted as markdown for additional context. However in order to do that I'd need to reverse engineer your document format, or go find the code that defines it in the main gitbook repo.

If I'm wrong about this, and the document format is documented somewhere, please make it more discoverable from the docs pages, as I've searched around and come up empty-handed.

Start with the documentation pages for endpoints that return page content and the document format mentioned in the issue. Trace how AI search source section keys relate to that response, then document the format and link it from the relevant docs so users can find it and use it to retrieve sections as markdown.