update readme

update readme with twitter and Facebook links

README.md

@@ -6,10 +6,11 @@ board and a development environment that implements the Processing/Wiring
 language. Arduino can be used to develop stand-alone interactive objects or
 can be connected to software on your computer (e.g. Flash, Processing, MaxMSP).
 The boards can be assembled by hand or purchased preassembled; the open-source
-IDE can be downloaded for free.
+IDE can be downloaded for free at http://arduino.cc/en/Main/Software
 
 * For more information, see the website at: http://www.arduino.cc/
-or the forums at: http://arduino.cc/forum/
+or the forums at: http://arduino.cc/forum/  
+You can also follow Arduino on twitter at: https://twitter.com/arduino or like Arduino on Facebook at: https://www.facebook.com/official.arduino
 
 * To report a *bug* in the software or to request *a simple enhancement* go to:
 http://github.com/arduino/Arduino/issues