Updating RSSI documentation

docs/Rssi.md

@@ -24,15 +24,15 @@ Connect the RSSI signal to any PWM input channel then set the RSSI channel as yo
 
 ## RSSI ADC
 
-Connect the RSSI signal to the RC2/CH2 input.  The signal must be between 0v and 3.3v to indicate between 0% and 100% RSSI.
-Use inline resistors to lower voltage if required, inline smoothing capacitors may also help.
+Connect the RSSI signal to the RC2/CH2 input. The signal must be between 0v and 3.3v.
+Use inline resistors to lower voltage if required; inline smoothing capacitors may also help.
+A simple PPM->RSSI conditioner can easily be made. See the  PPM-RSSI conditioning.pdf  for details.
 
-FrSky D4R-II and X8R supported.
+Under CLI :
+- enable using the RSSI_ADC feature  :  feature RSSI_ADC
+- set the RSSI_SCALE parameter (between 1 and 255) to adjust RSSI level according to your configuration.
 
-Enable using the RSSI_ADC feature:
 
-```
-feature RSSI_ADC
-```
+FrSky D4R-II and X8R supported.
 
 The feature can not be used when RX_PARALLEL_PWM is enabled.