Working with Orchestrator became much simpler in the last year. As more and more people and companies adopt Orchestrator for their automation, many more publications and posts are created. The following listing is essentially a snapshot of the most used resources.
The official documentation for Orchestrator can be found on the VMware website. Go to https://www.vmware.com/support/pubs/orchestrator_pubs.html.
Please note that you can select the version you want to have the documentation for. It's always a good idea to read the Release Notes to understand changes to the current version.
There are not that many books on Orchestrator. Actually, there are only three books that I know of, counting the ...