fixup! legacy description

Co-authored-by: Antoine du Hamel <duhamelantoine1995@gmail.com>

Author: VoltrexKeyva

doc/api/util.md

@@ -406,7 +406,7 @@ changes:
     description: The `constructor` parameter can refer to an ES6 class now.
 -->
 
-> Stability: 3 - Legacy: It is recommended to use ES6 class `extends` instead.
+> Stability: 3 - Legacy: Use ES2015 class syntax and `extends` keyword instead.
 
 * `constructor` {Function}
 * `superConstructor` {Function}