Collating a collection into one book

I think at some point I read that there would be a feature enabling collation of books in a given collection into a single publishable book. I have panned through the documentation and am not finding that. Is it a feature, or am I remembering incorrectly?

We call that feature a “folio”, but we don’t have a publicly released way to make folios. If you have a collection read to go, we can work with you individually to do it.