Update README.md adding FB 6490 (openhab#5900)

Added Fritz Box 6490 Cable (v7.02) as working and supported model.

Signed-off-by: dirkbe <[email protected]>

Author: dirkbe

bundles/binding/org.openhab.binding.fritzboxtr064/README.md

@@ -9,6 +9,7 @@ It has been tested on:
 * 7360SL (v6.30)
 * 7390
 * 6360 Cable (v6.04)
+* 6490 Cable (v7.02)
 * 7490
 * 7590 (v6.92)