Update README.md

Author: SteveWilkes

README.md

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 # AgileMapper
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+[![NuGet version](https://badge.fury.io/nu/AgileObjects.AgileMapper.svg)](https://badge.fury.io/nu/AgileObjects.AgileMapper)
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 AgileMapper is a zero-configuration, [highly-configurable](https://github.com/agileobjects/AgileMapper/wiki/Configuration) object-object mapper with [viewable execution plans](https://github.com/agileobjects/AgileMapper/wiki/Using-Execution-Plans) 
 via a [static or instance](https://github.com/agileobjects/AgileMapper/wiki/Static-vs-Instance-Mappers) API. It targets [.NET Standard 1.0](https://docs.microsoft.com/en-us/dotnet/articles/standard/library) and .NET 4.0.