More virsh Documentation Oversites

Tried to add a disk to a VM, the documentation was lacking. Here's the virsh command:

virsh attach-disk vmname /dev/disk sdb

In this example, it will appear as /dev/sdb to the VM. Unfortunately, partprobe did not work, we had to reboot.

In this case, I've added it to two VMs with the anticipation of granting multiple write access via GFS. Stay tuned.