add tech support qr code

README.md

@@ -111,11 +111,13 @@ Java客户端不依赖任何框架，能够运行于所有Java运行时环境，
 # Support
 <table>
   <thead>
-    <th>Apollo配置中心技术支持②群<br />群号：904287263</th>
+    <th>Apollo配置中心技术支持③群<br />群号：742035428</th>
+    <th>Apollo配置中心技术支持②群<br />群号：904287263（已满）</th>
     <th>Apollo配置中心技术支持①群<br />群号：375526581（已满）</th>
   </thead>
   <tbody>
     <tr>
+      <td><img src="https://raw.githubusercontent.com/ctripcorp/apollo/master/doc/images/tech-support-qq-3.png" alt="tech-support-qq-3"></td>
       <td><img src="https://raw.githubusercontent.com/ctripcorp/apollo/master/doc/images/tech-support-qq-2.png" alt="tech-support-qq-2"></td>
       <td><img src="https://raw.githubusercontent.com/ctripcorp/apollo/master/doc/images/tech-support-qq-1.png" alt="tech-support-qq-1"></td>
     </tr>