The previous commit added a way to configure firmware with -blockdev
rather than -drive if=pflash. Document it as the preferred way.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190308131445.17502-13-armbru@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>