ci: add action-badge (#498)

Author: erisu

README.md

@@ -23,6 +23,8 @@ description: Read/write files on the device.
 
 # cordova-plugin-file
 
+[![Android Testsuite](https://github.com/apache/cordova-plugin-file/actions/workflows/android.yml/badge.svg)](https://github.com/apache/cordova-plugin-file/actions/workflows/android.yml) [![Chrome Testsuite](https://github.com/apache/cordova-plugin-file/actions/workflows/chrome.yml/badge.svg)](https://github.com/apache/cordova-plugin-file/actions/workflows/chrome.yml) [![iOS Testsuite](https://github.com/apache/cordova-plugin-file/actions/workflows/ios.yml/badge.svg)](https://github.com/apache/cordova-plugin-file/actions/workflows/ios.yml) [![Lint Test](https://github.com/apache/cordova-plugin-file/actions/workflows/lint.yml/badge.svg)](https://github.com/apache/cordova-plugin-file/actions/workflows/lint.yml)
+
 This plugin implements a File API allowing read/write access to files residing on the device.
 
 This plugin is based on several specs, including :