update readme version

README.md

@@ -91,7 +91,7 @@ We deeply appreciate [community contributors](https://shardingsphere.apache.org/
 
 <hr>
 
-:white_check_mark: Version 5.2.0: released :tada:
+:white_check_mark: Version 5.2.1: released :tada:
 
 🔗 For the release notes, follow this link to the relevant [GitHub page](https://github.com/apache/shardingsphere/blob/master/RELEASE-NOTES.md).
 
@@ -147,7 +147,7 @@ With the client end connecting directly to the database, it provides services in
 <hr>
 
 [![Nightly-Download](https://img.shields.io/static/v1?label=nightly-builds&message=download&color=orange)](https://nightlies.apache.org/shardingsphere/)
-[![Download](https://img.shields.io/badge/release-download-orange.svg)](https://www.apache.org/dyn/closer.lua/shardingsphere/5.2.0/apache-shardingsphere-5.2.0-shardingsphere-proxy-bin.tar.gz)
+[![Download](https://img.shields.io/badge/release-download-orange.svg)](https://www.apache.org/dyn/closer.lua/shardingsphere/5.2.1/apache-shardingsphere-5.2.1-shardingsphere-proxy-bin.tar.gz)
 [![Docker Pulls](https://img.shields.io/docker/pulls/apache/shardingsphere-proxy.svg)](https://store.docker.com/community/images/apache/shardingsphere-proxy)
 
 A transparent database proxy, providing a database server that encapsulates database binary protocol to support heterogeneous languages. 

README_ZH.md

@@ -78,7 +78,7 @@ ShardingSphere 已于 2020 年 4 月 16 日成为 [Apache 软件基金会](https
 
 <hr>
 
-:white_check_mark: Version 5.2.0: 已发布 :tada:
+:white_check_mark: Version 5.2.1: 已发布 :tada:
 
 🔗 请访问 [发布说明](https://github.com/apache/shardingsphere/blob/master/RELEASE-NOTES.md) 获得更详细的信息.
 
@@ -112,7 +112,7 @@ Apache ShardingSphere 由 JDBC、Proxy 这 2 款既能够独立部署，又支
 <hr>
 
 [![Nightly-Download](https://img.shields.io/static/v1?label=nightly-builds&message=download&color=orange)](https://nightlies.apache.org/shardingsphere/)
-[![Download](https://img.shields.io/badge/release-download-orange.svg)](https://www.apache.org/dyn/closer.lua/shardingsphere/5.2.0/apache-shardingsphere-5.2.0-shardingsphere-proxy-bin.tar.gz)
+[![Download](https://img.shields.io/badge/release-download-orange.svg)](https://www.apache.org/dyn/closer.lua/shardingsphere/5.2.1/apache-shardingsphere-5.2.1-shardingsphere-proxy-bin.tar.gz)
 [![Docker Pulls](https://img.shields.io/docker/pulls/apache/shardingsphere-proxy.svg)](https://store.docker.com/community/images/apache/shardingsphere-proxy)
 
 定位为透明化的数据库代理端，提供封装了数据库二进制协议的服务端版本，用于完成对异构语言的支持。