Log Message:
ruby-asciidoctor: Add version 2.0.10

Import this package from wip because it is needed by games/warzone2100 for
documentation generation in replacement of textproc/asciidoc from 3.4.
This package can be safely added since CVE-2018-18385 has been fixed in 1.5.8
(https://github.com/asciidoctor/asciidoctor/issues/2888).