fix mixin example

yyx990803 · yyx990803 · commit b5052b57feb6 · 2015-03-28T13:12:20.000-04:00
diff --git a/source/guide/extending.md b/source/guide/extending.md
@@ -9,7 +9,7 @@ Mixins are a flexible way to distribute reusable functionalities for Vue compone
 
 ``` js
 // mixin.js
-exports.mixin = {
+module.exports = {
   created: function () {
     this.hello()
   },
