* remove unused workflows, scripts, and configuration (now handled by docs-build branch)
* upgrade Antora to 3.1 (and Node.js to 16)
* tune playbook settings
* reconfigure docs build for local build only
* add patch to support using linked worktree as Antora content source
* remove Antora extensions not needed for local builds
This makes it so that the URL contains security in the root of the deploy
folder. We will do this until we decide to add projects other than the
security related projects.
Dan Allen
Rob Winch