Comment 27 for bug 1848524

I have pushed a somewhat squashed version of the branch to master for inclusion in 3.6, including follow-ups that

- move a couple straggler files to TechRef
- sync up the installation documentation
- tweak generate_docs.pl a bit so that it can work with fewer global requirements and no need for sudo
- implement the docs-antora => docs move
- add release notes

Thanks, Remington, Blake, Jane, and the rest of DIG!