I don't really think documentation on ACLs belongs in the virsh description. The ACLs facility is a flexible feature that applies to all libvirt client connections. We shouldn't given the impression that its only useful for virsh.
As well as the docs on the website
there is this blog post on the subject
That virtualization guide you link to seems to contain little to no useful information about libvirt at all. I think this docs on ACLs belongs in the proper virtualization administrator guide.