Disable Asciidoc tests requiring DocBook if not installed
Disable Asciidoc tests requiring DocBook if not installed

The toolchain is too heavy for CI. Gotta wait for me to finish
the work on Asciideck for building HTML pages.

ninenines/erlang.mk,jj1bdx/erlang.mk,crownedgrouse/erlang.mk,rabbitmq/erlang.mk