Better document how to clone a AHV VM with Terraform Provider

[fabricekrebs]

The actual documentation doesn't describe how to clone a VM with the terraform provider.

It should be documented somewhere, that 2 sections should be defined, the parent_reference and the data_source_reference as well, like in the below example :

  parent_reference = {
    kind = "vm"
    name = "template-ubuntu1804"
    uuid = "a2563300-3f03-404d-9b40-aac3297b8c26"
  }


  disk_list {
    data_source_reference = {
      kind = "vm"
      name = "template-ubuntu1804"
      uuid = "a2563300-3f03-404d-9b40-aac3297b8c26"
    }
  }

Like explained on this existing issue, the documentation should be improved : https://github.com/nutanix/terraform-provider-nutanix/issues/263