updated the README file with the xunit report generation details
updated the README file with the xunit report generation details

cookchristopher/BackstopJS,garris/BackstopJS,mirzazeyrek/BackstopJS,mirzazeyrek/BackstopJS,klausbayrhammer/BackstopJS,garris/BackstopJS,garris/BackstopJS,cookchristopher/BackstopJS,klausbayrhammer/BackstopJS