Update README.md

Add note how to rollback driver on windows.

README.md

@@ -59,6 +59,8 @@ No additional setup required.
  5. Select ```J-Link (Interface 2)``` from the device dropdown
  6. Click ```Replace Driver```
  
+__NOTE__: To roll back to the original driver go to: Device Manager -> Open Device -> Update Driver
+
 ### Flashing a SoftDevice
 
  1. ```cd <SKETCHBOOK>```, where ```<SKETCHBOOK>``` is your Arduino Sketch folder: