docs:Fix typo

baooab · web-flow · commit 5bda2fdb5308 · 2017-12-26T09:03:51.000+08:00
The type of `value` is number, not string.
diff --git a/docs/iterator.md b/docs/iterator.md
@@ -69,9 +69,9 @@ function makeIterator(array) {
 ```javascript
 var it = idMaker();
 
-it.next().value // '0'
-it.next().value // '1'
-it.next().value // '2'
+it.next().value // 0
+it.next().value // 1
+it.next().value // 2
 // ...
 
 function idMaker() {
