Fix small typo in README (#142)

Just a missing comma in the configuration example.

Fixes #149

README.md

@@ -33,7 +33,7 @@ module.exports = function(config) {
       useBrowserName: true, // add browser name to report and classes names
       nameFormatter: undefined, // function (browser, result) to customize the name attribute in xml testcase element
       classNameFormatter: undefined, // function (browser, result) to customize the classname attribute in xml testcase element
-      properties: {} // key value pair of properties to add to the <properties> section of the report
+      properties: {}, // key value pair of properties to add to the <properties> section of the report
       xmlVersion: null // use '1' if reporting to be per SonarQube 6.2 XML format
     }
   });