update chinese api doc

Author: dabeng

README.md

@@ -1,6 +1,6 @@
 ![OrgChart](http://dabeng.github.io/OrgChart/img/heading.svg)
 
-**Read this in other languages: [简体中文](https://github.com/dabeng/OrgChart/blob/master/README.zh-cn.md)**
+# Read this in other languages: [简体中文](https://github.com/dabeng/OrgChart/blob/master/README.zh-cn.md)
 
 # [ES6 Version](http://github.com/dabeng/OrgChart.js)
 # [Web Components Version](http://github.com/dabeng/OrgChart-Webcomponents)

README.zh-cn.md

@@ -1,5 +1,7 @@
 ![OrgChart](http://dabeng.github.io/OrgChart/img/heading.svg)
 
+# Read this in other languages: [English](https://github.com/dabeng/OrgChart/blob/master/README.md)
+
 # [ES6版](http://github.com/dabeng/OrgChart.js)
 # [Web Components版](http://github.com/dabeng/OrgChart-Webcomponents)
 # [Vue.js版](https://github.com/dabeng/vue-orgchart)