Add G25/G27 shifters to README

Author: dmadison

README.md

@@ -23,7 +23,8 @@ Run one of the library examples in the Arduino IDE by going to `File -> Examples
 ### Commercial Devices
 * [Logitech Two Pedal Peripheral (Gas, Brake)](http://dmadison.github.io/Sim-Racing-Arduino/docs/logitech_pedals.html)
 * [Logitech Three Pedal Peripheral (Gas, Brake, Clutch)](http://dmadison.github.io/Sim-Racing-Arduino/docs/logitech_pedals.html)
-* [Logitech Driving Force Shifter](http://dmadison.github.io/Sim-Racing-Arduino/docs/logitech_shifter.html)
+* [Logitech Driving Force Shifter (G923 / G920 / G29)](http://dmadison.github.io/Sim-Racing-Arduino/docs/logitech_shifter.html)
+* [Logitech G25 / G27 Shifter](http://dmadison.github.io/Sim-Racing-Arduino/docs/logitech_shifter_g25.html)
 
 ## Adapters