add coverage badge

README.md

@@ -1,5 +1,6 @@
 # BaristApp
 
+![coverage][coverage_badge]
 [![style: very good analysis][very_good_analysis_badge]][very_good_analysis_link]
 [![License: MIT][license_badge]][license_link]
 
@@ -160,6 +161,7 @@ Update the `CFBundleLocalizations` array in the `Info.plist` at `ios/Runner/Info
 Main page asset: barista and coffee by monkik from [Noun Project][barista_asset_link]
 
 [barista_asset_link]: https://thenounproject.com/browse/icons/term/barista-and-coffee/
+[coverage_badge]: coverage_badge.svg
 [flutter_localizations_link]: https://api.flutter.dev/flutter/flutter_localizations/flutter_localizations-library.html
 [internationalization_link]: https://flutter.dev/docs/development/accessibility-and-localization/internationalization
 [license_badge]: https://img.shields.io/badge/license-MIT-blue.svg