update synthe

docs/vhdl/synthe.md

@@ -275,7 +275,7 @@ You have a Digital Synthesizer !
 
 So now, let's play ~~MUSIC!~~ tones!
 
-4 types of waveform can be played with switches sw1 and sw0: sine (00), square (01), triangle (10), saw-tooth (11).
+4 types of waveform can be played with switches {sw1,sw0}: sine (00), square (01), triangle (10), saw-tooth (11).
 
 Keys A R Y P ^ are used to play 5 tones:
 
@@ -291,7 +291,7 @@ Do Do Si-b Do Sol Sol Do Fa Mi Do
 
 Y  Y   R   Y   A   A   Y  ^  P  Y
 
-You can combine up to 4 harmonics with the fundamental tone thanks to switches sw2 to sw5.
+You can combine up to 4 harmonics with the fundamental tone thanks to switches sw2 to sw5 (OFF to suppress an harmonic, ON to add it)
 
 If you want to add tones associated to other keys, edit the file `synthesizer.vhd`.
 To apply the good scancode, check this: