Implementing Hierarchy in PDFs

[krrome]

Hi @vagenas,

I am referring to #287 where I left a comment.
I have managed to solve the problem for my use cases, before attempting to implemented a proposal for a PR I would like to discuss here whether this path (using bookmarks) is aligned with your goals for docling pdf parsing. I have only spent 1 day digging through docling code, so please excuse any uglyness of the gist mentioned in comment #287 (comment).

I'd be glad to contribute to this great project if my approach makes sense.

Btw. I have created a new chat despite the existence of this vaguely related one: #510