Extract module description from a module's `package-info.java` Javadoc

[doggy-dev]

Is it possible to reuse Javadoc of a module's package-info.java for the generated documentation?
I'd expect it do be on the top of the module's canvas or underneath the title and above the diagram in an aggregated document.

[odrotbohm]

This seemed to be easy enough to add, so I quickly threw it together. Feel free to give the 2.0 snapshots a try!