Update blk.md

@@ -9,6 +9,6 @@ http://git.yoho.cn/yoho-documents/api-interfaces/tree/master/%E5%95%86%E5%93%81%
 ## 3、资源位接口文档
 http://git.yoho.cn/yoho-documents/api-interfaces/tree/master/%E8%B5%84%E6%BA%90%E4%BD%8D#2%E8%8E%B7%E5%8F%96%E8%B5%84%E6%BA%90%E4%BD%8D%E6%8E%A5%E5%8F%A3
 
-## 4、支付接口文档
+## 4、订单支付接口文档
 
 http://git.yoho.cn/yoho-documents/api-interfaces/tree/master/%E6%94%AF%E4%BB%98
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