No chapter headings in the book

[notapatch]

There are no chapter headings in the book. It makes it difficult to find where you are in the book.
I'm using EPUB but checking PDF it looks missing as well..

[madeindjs]

I think this is a bug from https://github.com/asciidoctor/asciidoctor-epub3 wich produce a different document than https://github.com/asciidoctor/asciidoctor-pdf.

I will try to take a look if there are a solution.