Support mdBook-specific features: `#include` and `#rustdoc_include`

[hustcer]

Hi,
Thanks for the great work!
While I'm creating The Rust Programming Language epub from https://github.com/rust-lang/book.git found that some mdBook-specific features like #include and #rustdoc_include were not supported, can you add these features? Or any work around? Thanks again.

[crowdagger]

Hi !

Sorry for the huge delay in answering.

Honestly, this feels quite specific to a target that’s really not mine. I am not against accepting a PR for this if someone submits it, but given the little time I have to give to this project currently this doesn’t seem as a priority :/

[hustcer]

Yeah, agree, this is not of high priority, thanks for your reply