docs: Change README.md

README.md

@@ -146,6 +146,8 @@ Children of `<KeepAlive>` will be cached, but we have to make sure that `<KeepAl
 
 `disabled`: When we don't need components for caching, we can disable it; the disabled configuration will only takes effect when the component's status changes from unactive to active.
 
+**Note**: `<KeepAlive>` The innermost outer layer of the packaged component must have a real DOM tag.
+
 #### Example
 ```JavaScript
 import React from 'react';
@@ -164,6 +166,7 @@ import {
 class One extends React.Component {
   render() {
     return (
+      // a real DOM tag
       <div>This is One.</div>
     );
   }

README.zh-CN.md

@@ -148,6 +148,8 @@ npm install react-router@next react-router-dom@next
 
 `disabled`：当我们不需要缓存组件时，我们可以禁用它；禁用仅在组件从未激活状态变为激活状态时生效。
 
+**注意**：`<KeepAlive>` 包裹的组件内部最外层必须有一个真实的 DOM 标签。
+
 
 #### 例子
 ```JavaScript

package.json

 {
   "name": "react-keep-alive",
-  "version": "2.0.0-alpha.0",
+  "version": "2.0.0",
   "description": "Package will allow components to maintain their status, to avoid repeated re-rendering.",
   "author": "Shen Chang",
   "homepage": "https://github.com/Sam618/react-keep-alive",