added chmod

README.md

@@ -29,6 +29,7 @@ To prepare a qemu disk as installation target run following commands and set `di
 ```
 img="/var/lib/libvirt/images/ts-linux-testing.qcow2"
 qemu-img create -f qcow2 -o size=20G $img  # create image
+chown libvirt-qemu:libvirt-qemu $img       # make accessable for qemu
 qemu-nbd -c /dev/nbd0 $img  # create device from image
 qemu-nbd -d /dev/nbd0       # release device
 ```