Update RX UART protocol configuration for MAVLink

Author: thespova

docs/software/mavlink.md

@@ -61,7 +61,7 @@ The minimum versions to use this feature are:
 
 1. Turn on both the RX and TX, and ensure they are bound, connected, and communicating. In the ELRS LUA scrip look for a C in the top-right corner of the screen which indicates that the TX module and receiver are connected and communicating.
 
-1. Configure protocol on the RX UART.
+1. Set the protocol on the RX UART to MAVLink.
    - For ELRS v3, with the TX and RX still connected, in the ELRS LUA script, select `Other Devices`, select your receiver, and set the `serial protocol` to `MAVLink`.
    - For ELRS v4, this step can be skipped. RX protocol is now configured automatically when changing the TX mode to MAVLink.