README.md in alipay-0.7.0 vs README.md in alipay-0.7.1

@@ -7,11 +7,11 @@
 ## Installation
 
 Add this line to your application's Gemfile:
 
 ```ruby
-gem 'alipay', '~> 0.7.0'
+gem 'alipay', '~> 0.7.1'
 ```
 
 And then execute:
 
 ```console
@@ -313,11 +313,13 @@
 | Key | Requirement | Description |
 | --- | ----------- | ----------- |
 | out_trade_no | required | Order number in your application. |
 | subject | required | Order subject. |
 | currency | required | Abbreviated currency name. |
-| total_fee | required | Order total price. |
+| total_fee | required * | Order total price. |
 | notify_url | optional | Alipay asyn notify url. |
+
+\* total_fee can be replace by rmb_fee.
 
 ### 境外收单单笔退款接口
 
 #### Name