Put a comment in sample config about one target required by Grunt to run properly
Put a comment in sample config about one target required by Grunt to run properly

ref: #21

spinningarrow/grunt-protractor-runner,christian-bromann/grunt-protractor-runner,rohitkadam19/grunt-protractor-runner,sullivanpt/grunt-protractor-runner,lmacneil/grunt-protractor-runner,rbrcurtis/grunt-protractor-runner,teerapap/grunt-protractor-runner