I will pass that onto the documentation team.
What are you trying to do with Java and AEM 6. For example - are you trying to write a custom AEM service.
If so - see:
http://helpx.adobe.com/experience-manager/using/first-osgi.html
If you want to use Slightly and Java, new articles will be written - but that topic will get your started.
In the meantime -- there are many how to articles that talks about using Java and AEM to perform specific use cases. See:
http://helpx.adobe.com/marketing-cloud/experience-manager.html