Update README.md

Added build badge for github actions

Author: frankodoom

README.md

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 # CountryData.Standard
 :earth_africa: A simple cross platform offline .NET library for getting Global Country Data without making any HTTP calls.
 
-### Nuget
 
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-| downloads | ![](https://img.shields.io/nuget/dt/CountryData.Standard) |
+| nuget downloads | ![](https://img.shields.io/nuget/dt/CountryData.Standard) |
+| builds | [![.NET](https://github.com/frankodoom/CountryData.Standard/actions/workflows/dotnet.yml/badge.svg?branch=master)](https://github.com/frankodoom/CountryData.Standard/actions/workflows/dotnet.yml) |
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 ### Install Library