Update README.md

README.md

 # React Keep Alive
-
-Writing.
+Package will allow components to maintain their status, to avoid repeated re-rendering.
 
 ## TODO
 - MAX
 - wrappedComponent
 - document
 - test
+
+## Installation
+React Keep Alive requires React 16.3 or later.
+
+To use React Keep Alive with your React app:
+
+```bash
+npm install --save react-keep-alive
+```
+
+## Changelog
+Changes are tracked in the [CHANGELOG.md](https://github.com/Sam618/react-keep-alive/blob/master/CHANGELOG.md).
+
+
+## License
+React Keep Alive is available under the [MIT](https://github.com/Sam618/react-keep-alive/blob/master/LICENSE) License.