Update README.md

Author: froque

README.md

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 # VSIXInteropFormsToolkit
 Visual Studio extension, with command tool to generate interop wrapper classes. adapted from add-in.
 
+[![Build Status](https://froque.visualstudio.com/VSIXInteropFormsToolkit/_apis/build/status/VSIXInteropFormsToolkit-.NET%20Desktop-CI?branchName=master)](https://froque.visualstudio.com/VSIXInteropFormsToolkit/_build/latest?definitionId=1&branchName=master)
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  * [VSIXInteropFormsToolkit in Visual Studio Marketplace](https://marketplace.visualstudio.com/items?itemName=filiperoque.VSIXInteropFormsToolkit) 
 
 See: