README.md in alipay-0.0.2 vs README.md in alipay-0.0.3

@@ -13,11 +13,11 @@
 ## Installation
 
 Add this line to your application's Gemfile:
 
 ```ruby
-gem 'alipay', '~> 0.0.2'
+gem 'alipay', '~> 0.0.3'
 ```
 
 or development version
 
 ```ruby
@@ -78,9 +78,25 @@
 }
 
 Alipay::Service.send_goods_confirm_by_platform(options)
 # => '<!xml version="1.0" encoding="utf-8"?><alipay><is_success>T</is_success></alipay>'
 ```
+
+### Refund
+
+```ruby
+batch_no = Alipay::Utils.generate_batch_no # refund batch no, you SHOULD store it to db to avoid alipay duplicate refund
+options = {
+    batch_no:   batch_no,
+    data:       [{:trade_no => 'TRADE_NO', :amount => '10.0', :reason => 'REFUND_REASON'}],
+    notify_url: 'YOUR_ORDER_NOTIFY_URL'  # https://writings.io/orders/20130801000001/alipay_refund_notify
+}
+
+Alipay::Service.create_refund_url(options)
+```
+
+Batch No. Generate Demo: http://git.io/GcXKJw
+Notify Url Demo: http://git.io/pst4Tw
 
 ### Verify notify
 
 ```ruby
 # example in rails