Update README.md

Author: myloveCc

README.md

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 # NETCore.Encrypt [中文文档](http://www.cnblogs.com/piscesLoveCc/p/7423205.html)
 [![NuGet](https://img.shields.io/nuget/v/NETCore.Encrypt.svg)](https://nuget.org/packages/NETCore.Encrypt)
 [![NETCore CLR](https://img.shields.io/badge/.NETCore%20Clr-2.0-brightgreen.svg)](https://www.microsoft.com/net/core)
-[![NetStandard 2.0](https://img.shields.io/badge/NetStandard-2.0-orange.svg)](https://www.microsoft.com/net/core)
+[![NetStandard 2.0.3](https://img.shields.io/badge/NetStandard-2.0.3-orange.svg)](https://www.microsoft.com/net/core)
 [![license](https://img.shields.io/github/license/myloveCc/NETCore.Encrypt.svg)](https://github.com/myloveCc/NETCore.Encrypt/blob/master/License)
 
 NETCore encrypt and decrpty tool，Include AES，RSA，MD5，SAH1，SAH256，SHA384，SHA512 and more