Adding link for PySerial

README.md

@@ -23,7 +23,7 @@ Dependencies
   Cura is built on top of the Uranium framework.
 * [CuraEngine](https://github.com/Ultimaker/CuraEngine)
   This will be needed at runtime to perform the actual slicing.
-* PySerial
+* [PySerial](https://github.com/pyserial/pyserial)
   Only required for USB printing support.
 
 Configuring Cura