Use ES6 syntax in README examples
Use ES6 syntax in README examples

mathiasbynens/xregexp,slevithan/xregexp,mathiasbynens/xregexp,GerHobbelt/xregexp,mathiasbynens/xregexp,slevithan/xregexp,slevithan/xregexp,GerHobbelt/xregexp,slevithan/XRegExp,mathiasbynens/xregexp,GerHobbelt/xregexp,slevithan/XRegExp