Pisound: Added README entry for pisound-pi5 overlay.

Signed-off-by: Giedrius Trainavičius <giedrius@blokas.io>

Author: gtrainavicius

arch/arm/boot/dts/overlays/README

@@ -3486,11 +3486,17 @@ Params: speed                   Display SPI bus speed
 
 
 Name:   pisound
-Info:   Configures the Blokas Labs pisound card
+Info:   Configures the Blokas Labs Pisound card
 Load:   dtoverlay=pisound
 Params: <None>
 
 
+Name:   pisound-pi5
+Info:   Pi 5 specific overlay override for Blokas Labs Pisound card, see pisound
+Load:   dtoverlay=pisound-pi5
+Params: <None>
+
+
 Name:   pitft22
 Info:   Adafruit PiTFT 2.2" screen
 Load:   dtoverlay=pitft22,<param>=<val>