[denonmarantz] Update protocol reference in readme (#10044)
[denonmarantz] Update protocol reference in readme (#10044)

Signed-off-by: Hilbrand Bouwkamp <ec356b91542503fa798a0780c99113e8c2be2b02@h72.nl>
paulianttila/openhab2,paulianttila/openhab2,paulianttila/openhab2