Upgrade Asciidoctor to 2.0.12
What does this MR do?
Upgrade Asciidoctor to version 2.0.12 (from 2.0.10).
Version 2.0.11 should improve stability as it fixes two infinite loop scenarios: https://github.com/asciidoctor/asciidoctor/releases/tag/v2.0.11
~"group::editor" devopscreate asciidoc Technical Writing
Edited by Guillaume Grossetie