add azure pipelines badge to readme [ci skip]

Author: krakjoe

README.md

@@ -16,6 +16,7 @@ License v3.01.
 
 [![Build status](https://travis-ci.org/php/php-src.svg?branch=master)](https://travis-ci.org/php/php-src)
 [![Build status](https://ci.appveyor.com/api/projects/status/meyur6fviaxgdwdy?svg=true)](https://ci.appveyor.com/project/php/php-src)
+[![Build Status](https://dev.azure.com/krakjoe/php/_apis/build/status/php.php-src?branchName=PHP-7.4)](https://dev.azure.com/krakjoe/php/_build/latest?definitionId=1&branchName=PHP-7.4)
 
 ## Documentation