updated api version in readme

Author: y2chaits

README.md

@@ -3,7 +3,7 @@ WePay-Java-SDK
 
 Note
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-This WePay-Java-SDK is for <a href = "https://www.wepay.com/developer/version/2015-03-30">WePay Api Version 2015-03-30</a>. The jar for the previous API versions can be found in the lib folder.
+This WePay-Java-SDK is for <a href = "https://www.wepay.com/developer/version/2016-06-22">WePay Api Version 2016-06-22</a>. The jar for the previous API versions can be found in the lib folder.
 
 Building
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