Update article.md

Typo: "there" -> "their"

1-js/06-advanced-functions/03-closure/article.md

@@ -599,7 +599,7 @@ function f() {
 }
 
 let g = f(); // while g is alive
-// there corresponding Lexical Environment lives
+// their corresponding Lexical Environment lives
 
 g = null; // ...and now the memory is cleaned up
 ```