Update README.md

added code coverage badge counter to point to dev branch

Author: frankodoom

README.md

@@ -11,7 +11,7 @@ A simple cross-platform offline .NET library for getting Global Country Data wit
 |-|-|
 | nuget downloads | [![](https://img.shields.io/nuget/dt/CountryData.Standard)](https://www.nuget.org/packages/CountryData.Standard) |
 | builds | ![.NET](https://github.com/frankodoom/CountryData.Standard/actions/workflows/dotnet.yml/badge.svg?branch=master) |
-|code coverage|[![codecov](https://codecov.io/github/frankodoom/CountryData.Net/graph/badge.svg?token=E79CY267AR)](https://codecov.io/github/frankodoom/CountryData.Net)
+|code coverage|[![codecov](https://codecov.io/github/frankodoom/CountryData.Net/branch/development/graph/badge.svg?token=E79CY267AR)](https://codecov.io/github/frankodoom/CountryData.Net)