add build status badge

README.md

@@ -1,4 +1,5 @@
 # QR Code Scanner
+[![Build Status](https://dev.azure.com/juliuscanute/spring/_apis/build/status/juliuscanute.qr_code_scanner?branchName=master)](https://dev.azure.com/juliuscanute/spring/_build/latest?definitionId=7&branchName=master)
 
 A QR code scanner that works on both iOS and Android by natively embedding the platform view within Flutter. The integration with Flutter is seamless, much better than jumping into a native Activity or a ViewController to perform the scan.