*: add example usage binaries about go-qemu

[robertojrojas]

@mdlayher I would like to help with this issue. Can you clarify what you mean by "binaries"?

[benlemasurier]

@mdlayher can probably elaborate but I believe he means example programs i.e., examples/power_off/main.go

[robertojrojas]

cool beans. I'll start working on some.

[mdlayher]

Yep, that's exactly it. I want to provide some binaries that show how to use these packages.

Another idea is something like hvls, which is more or less virsh list, and shows all the VMs running on a hypervisor.