Update README.md

Author: Kruemelbahn

README.md

@@ -7,4 +7,4 @@ http://arduino.cc/playground/Main/I2CPortExpanderAndKeypads
 Changes where made by me regarding 'PIN MAPPING' and 'num_cols' to fit with my 4x4 keypads
 used with ([DISPA](http://www.github.com/Kruemelbahn/DISPA) or [LocoIO-Editor](http://www.github.com/Kruemelbahn/LocoIO-Editor))
 
-Please read also the comment in is2keypad.cpp for more informations.
+Please read also the comment in i2ckeypad.cpp for more informations.