I'm sorry to say that there is no Remoting 3 documentation, as yet. For now, we'll have to consider it "self documenting".
I Can't believe it...!!! The library is not exactly "self documenting". I'm really disappointed about JBoss AS, and I'll consider using any other EE server.
Any examples or short getting started guide could greatly help new users with no prior experience. A couple of hours spend to write a getting started guide, be it unpolished, can greatly help because once you have something working javadocs are fine. Otherwise it takes a lot of time to make just the first step.
update: Maybe this is what I was looking for: https://community.jboss.org/wiki/JBossRemoting3HelloWorldSample