update README.md new library

fernandofussuma · fernandofussuma · commit 2e0851bed843 · 2015-12-30T14:13:36.000-02:00
diff --git a/README.md b/README.md
@@ -8,6 +8,7 @@ http://learn.adafruit.com/drive-a-16x2-lcd-directly-with-a-raspberry-pi/overview
 
 install:
 ```
+sudo gem install rpi_gpio
 sudo gem install charlcd
 ```
 
