Use Javadoc as source for the reference documentation

[obfischer]

I discussed with Michael the idea of using our Javadoc as source for our Asciidoctor based documentation. The idea is to have e.g. the definition of label A and relation B written as Javadoc in Asciidoctor and to include the relevant parts via Asciidoctor's include statement.

This would require to switch from the standard Javadoclet to the Asciidoctor doclet for writing our Javadoc.

We see here a lot of potential to have the relevant documention maintained in one place and not in many.

Please comment our sight on this in this comment.

[obfischer]

See https://github.com/asciidoctor/asciidoclet for information on writing Javadoc with Asciidoctor.