📝 编写文档

README.md

@@ -48,7 +48,7 @@
             <td align="center" width="200"><a href="#授权Teambition"><img src="https://gitee.com/yadong.zhang/static/raw/master/JustAuth/teambition.png" width="20"></a></td>
             <td align="center" width="200"><a href="#授权人人"><img src="https://gitee.com/yadong.zhang/static/raw/master/JustAuth/renren.png" width="20"></a></td>
             <td align="center" width="200"><a href="#授权Pinterest"><img src="https://gitee.com/yadong.zhang/static/raw/master/JustAuth/pinterest.png" width="20"></a></td>
-            <td align="center" width="200"><a href="#授权Stack Overflow"><img src="" width="20"></a></td>
+            <td align="center" width="200"><a href="#授权Stack Overflow"><img src="https://gitee.com/yadong.zhang/static/raw/master/JustAuth/stackoverflow.png" width="20"></a></td>
             <td align="center" width="200"><a href="#授权csdn"><img src="https://gitee.com/yadong.zhang/static/raw/master/JustAuth/csdn.png" width="20"></a></td>
         </tr>
     </table>
@@ -131,6 +131,7 @@ authRequest.login(callback);
 |  <img src="https://gitee.com/yadong.zhang/static/raw/master/JustAuth/teambition.png" width="20">  | [AuthTeambitionRequest](https://gitee.com/yadong.zhang/JustAuth/blob/master/src/main/java/me/zhyd/oauth/request/AuthTeambitionRequest.java) | <a href="https://docs.teambition.com/" target="_blank">参考文档</a> |
 |  <img src="https://gitee.com/yadong.zhang/static/raw/master/JustAuth/renren.png" width="20">  | [AuthRenrenRequest](https://gitee.com/yadong.zhang/JustAuth/blob/master/src/main/java/me/zhyd/oauth/request/AuthRenrenRequest.java) | <a href="http://open.renren.com/wiki/OAuth2.0" target="_blank">参考文档</a> |
 |  <img src="https://gitee.com/yadong.zhang/static/raw/master/JustAuth/pinterest.png" width="20">  | [AuthPinterestRequest](https://gitee.com/yadong.zhang/JustAuth/blob/master/src/main/java/me/zhyd/oauth/request/AuthPinterestRequest.java) | <a href="https://developers.pinterest.com/docs/api/overview/?" target="_blank">参考文档</a> |
+|  <img src="https://gitee.com/yadong.zhang/static/raw/master/JustAuth/stackoverflow.png" width="20">  | [AuthStackOverflowRequest](https://gitee.com/yadong.zhang/JustAuth/blob/master/src/main/java/me/zhyd/oauth/request/AuthStackOverflowRequest.java) | <a href="https://api.stackexchange.com/docs" target="_blank">参考文档</a> |
 |  <img src="https://gitee.com/yadong.zhang/static/raw/master/JustAuth/csdn.png" width="20">  |  [AuthCsdnRequest](https://gitee.com/yadong.zhang/JustAuth/blob/master/src/main/java/me/zhyd/oauth/request/AuthCsdnRequest.java)  |  无 |
 
 _请知悉：经咨询CSDN官方客服得知，CSDN的授权开放平台已经下线。如果以前申请过的应用，可以继续使用，但是不再支持申请新的应用。so, 本项目中的CSDN登录只能针对少部分用户使用了_

update.md

 ### 2019/07/18
 1. 合并github上[@pengisgood](https://github.com/pengisgood) 的[pr#19](https://github.com/zhangyd-c/JustAuth/pull/19)，集成人人
 2. 合并github上[@pengisgood](https://github.com/pengisgood) 的[pr#20](https://github.com/zhangyd-c/JustAuth/pull/20)，集成Pinterest
+2. 合并github上[@pengisgood](https://github.com/pengisgood) 的[pr#21](https://github.com/zhangyd-c/JustAuth/pull/21)，集成StackOverflow
 
 ### 2019/07/17
 1. 优化代码