Update RF-Protocol.md

The example implied you could only get hex values for the data.  SetOption28 changes it to decimal.  I've added that as a note.

Author: lengross

docs/RF-Protocol.md

@@ -64,6 +64,7 @@ This JSON payload data can be used in a rule such as:
 ```
 ON RfReceived#Data=<hex-value> DO <command> ENDON
 ```
+Note: If you need a decimal-value instead of a \<hex-value\> see [SetOption28](https://tasmota.github.io/docs/Commands/#setoption28).
 
 Examples:  
 **Sonoff RM433 Remote**