Improving the "ovirt_disk" documentation for disk extend flow.

If the disk is referenced by "name" and is attached to a VM,
make sure to specify "vm_name" / "vm_id" to prevent extension
of another disk that is not attached to the VM.

Signed-off-by: Pavel Bar <pbar@redhat.com>
Bug-Url: https://bugzilla.redhat.com/2016638

plugins/modules/ovirt_disk.py

@@ -73,6 +73,8 @@
             - "Size of the disk. Size should be specified using IEC standard units.
                For example 10GiB, 1024MiB, etc."
             - "Size can be only increased, not decreased."
+            - "If the disk is referenced by C(name) and is attached to a VM, make sure to specify C(vm_name)/C(vm_id)
+               to prevent extension of another disk that is not attached to the VM."
         type: str
     interface:
         description: