add maven central logo

README.md

@@ -3,12 +3,13 @@ Apollo（配置中心）
 
 [![Build Status](https://travis-ci.org/ctripcorp/apollo.svg?branch=master)](https://travis-ci.org/ctripcorp/apollo)
 [![GitHub release](https://img.shields.io/github/release/ctripcorp/apollo.svg)](https://github.com/ctripcorp/apollo/releases)
+![maven](https://img.shields.io/maven-central/v/com.ctrip.framework.apollo/apollo.svg)
 [![Coverage Status](https://coveralls.io/repos/github/ctripcorp/apollo/badge.svg?branch=master)](https://coveralls.io/github/ctripcorp/apollo?branch=master)
-[![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
 <a href="https://scan.coverity.com/projects/ctripcorp-apollo">
   <img alt="Coverity Scan Build Status" src="https://img.shields.io/coverity/scan/8244.svg"/>
 </a>
 [![codecov.io](https://codecov.io/github/ctripcorp/apollo/coverage.svg?branch=master)](https://codecov.io/github/ctripcorp/apollo?branch=master)
+[![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
 
 Apollo（阿波罗）是携程框架部门研发的分布式配置中心，能够集中化管理应用不同环境、不同集群的配置，配置修改后能够实时推送到应用端，并且具备规范的权限、流程治理等特性，适用于微服务配置管理场景。