SpringBoot Create a single PDF file with all the reference content

As discussed in a meeting, we should make a single PDF file with all of the reference content.

You can assign this issue to me (and I'll try to assign it to myself).

Comment From: philwebb

For those looking, the PDF version is linked at the very top of the HTML version. E.g. https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/ has

"This document is also available as multiple HTML pages and as a PDF."