work on docs

docs/nmt.html

@@ -20,8 +20,10 @@ Now run your base station on channel 1.
 Tune the transmitter to 463.000 MHz and the receiver to 453.000.
 You should tune the receiver to 463.000 first, to check if you hear the idle signal from the base station.
 Then tune to actually uplink frequency 453.000 MHz.
+(You may check the quality using '-L 2' command line option and build a radio loop by tuning the receiver to the transmitter.)
 </p>
 
+
 <pre>
 
 # src/nmt/nmt -k 1 -y SE,1