Update routing.md (vuejs#136)

* Update routing.md

* Update routing.md

* Update routing.md

Author: njleonzhang

zh/routing.md

@@ -36,8 +36,8 @@ export function createApp () {
     router,
     render: h => h(App)
   })
-  // 注入 router 到根 Vue 实例
-  return { app, router }
+  // 返回 app 和 router
+  return { app, router }
 }
 ```