Update README.md (#856)

Update CI status badge

Author: MarcoRossignoli

README.md

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 # Coverlet
 
-[![Build Status](https://dev.azure.com/tonerdo/coverlet/_apis/build/status/tonerdo.coverlet?branchName=master)](https://dev.azure.com/tonerdo/coverlet/_build/latest?definitionId=3&branchName=master) [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://github.com/tonerdo/coverlet/blob/master/LICENSE)
+[![Build Status](https://dev.azure.com/tonerdo/coverlet/_apis/build/status/coverlet-coverage.coverlet?branchName=master)](https://dev.azure.com/tonerdo/coverlet/_build/latest?definitionId=5&branchName=master) [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://github.com/tonerdo/coverlet/blob/master/LICENSE)
 
 Coverlet is a cross platform code coverage framework for .NET, with support for line, branch and method coverage. It works with .NET Framework on Windows and .NET Core on all supported platforms.