Fix invalid link to Ecmascript 2015 specification

Author: sidshank

javascript/ql/src/Metrics/FUseOfES6.qhelp

@@ -24,7 +24,7 @@ the migration.
 </recommendation>
 <references>
 <li>
-Ecma International: <a href="http://www.ecma-international.org/ecma-262/6.0">ECMAScript 2015 Language Specification</a>.
+Ecma International: <a href="https://262.ecma-international.org/6.0/">ECMAScript 2015 Language Specification</a>.
 </li>
 </references>
 </qhelp>