Expanded the authoring instructions.
The guidelines authoring instructions have been amended to:
· Recommend Asciidoctor as a lightweight way of previewing one's changes.
· Point out that there is a command-line program in rubygem-asciidoctor.
· Explain how the purpose of the container-based method differs from the purpose of the Asciidoctor method.
· Mention that the makefile will download container blobs.