Hint for using 433Mhz transmitter (#3521)

This has to be added in order for the example to work, otherwise the example won't work because homeassistant is expecting a feedback sensor (for 433 transmitters, there is usually no feedback from e.g. the RC-lightbulb)

components/remote_transmitter.rst

@@ -936,6 +936,7 @@ earlier, create a new template switch that sends the RF code when triggered:
     switch:
       - platform: template
         name: RF Power Button
+        optimistic: true
         turn_on_action:
           - remote_transmitter.transmit_rc_switch_raw:
               code: '100010000000000010111110'