add README_CN.md link in README.md

README.md

 # Pika
-
+## Introduction [中文] (https://github.com/baotiao/pika/blob/pika2.0/README_CN.md)
 [![Join the chat at https://gitter.im/baotiao/pika](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/baotiao/pika?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 Pika is a database that has the same feature as redis. And Pika is compability
 with redis client.