[sonos] improve docs, commands for control channel (openhab#6370)

* Fixed Sonos control channel commands

Signed-off-by: Fabian Woelk <fawel@gmx.de>
Signed-off-by: Hans-Reiner Hoffmann <hans-reiner.hoffmann@gmx.de>

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

@@ -52,7 +52,7 @@ The devices support the following channels:
 | alarmproperties | String | R | Properties of the alarm currently running | all |
 | alarmrunning | Switch | R | Set to ON if the alarm was triggered | all |
 | clearqueue | Switch | W | Suppress all songs from the current queue | all |
-| control | Player | RW | Control the Zone Player, e.g. start/stop/next/previous/ffward/rewind | all |
+| control | Player | RW | Control the Zone Player, e.g. PLAY/PAUSE/NEXT/PREVIOUS | all |
 | coordinator | String | R | UDN of the coordinator for the current group | all |
 | currentalbum | String | R | Name of the album currently playing | all |
 | currentalbumart | Image | R | Cover art of the album currently playing | all |