Update article.md

Adding "an". Making subject of second clause explicit (not necessary, but may improve readability).

Author: paroche

1-js/04-object-basics/06-constructor-new/article.md

@@ -136,7 +136,7 @@ Usually, constructors do not have a `return` statement. Their task is to write a
 
 But if there is a `return` statement, then the rule is simple:
 
-- If `return` is called with object, then it is returned instead of `this`.
+- If `return` is called with an object, then the object is returned instead of `this`.
 - If `return` is called with a primitive, it's ignored.
 
 In other words, `return` with an object returns that object, in all other cases `this` is returned.