Update README.md

Add clarification about jumper position before flashing

README.md

@@ -39,6 +39,7 @@ The previous version (based on repetier v0.91) can be found [here](https://githu
 1. With the machine off remove the back panel and short the jumper JP1 or J37 depending on model.  Some Boards do not have jumper pins exposed but can still be shorted with a conductive wire.
 2. Turn the machine on and wait a few seconds then turn it off again.  The machine will have been flashed removing the current stock firmware and allowing it to be detected as a normal arduino DUE. NOTE: Windows users may need to install drivers to detect the board.  Consult the Voltivo forums.   
 Note : points 1 and 2 are only needed to wipe the stock fw or a corrupted fw, for update they are not necessary.
+Note 2: remove the jumper before flashing if still there
 3. Use an arduino IDE supporting arduino DUE, [1.6.9](http://arduino.cc/en/Main/OldSoftwareReleases) with Due 1.6.8 module from board manager.
 4. Update variants.cpp arduino file with the one present in src\ArduinoDUE\AdditionalArduinoFile according your IDE version   
 NOTE: You do not need to compile arduino from source these files are in the arduino directory structure (click on preferences.txt in Files/Preferences dialog box).