minor. fix a link to a source file from README
minor. fix a link to a source file from README

Change-Id: I2f31c8d4fc8915449a3a14ebce7571386933ec3e

mahnazhaj/iot-starterkit,mahnazhaj/iot-starterkit,mahnazhaj/iot-starterkit,iwonahahn/iot-starterkit,iwonahahn/iot-starterkit,iwonahahn/iot-starterkit,iwonahahn/iot-starterkit,mahnazhaj/iot-starterkit,iwonahahn/iot-starterkit