Add a screenshot to the README

Author: Maurizio Branca

README.md

@@ -1,3 +1,7 @@
 # Alfred Arduino CLI
 
-Workflow to use the Arduino CLI from the Alfred launcher.
+Python based Workflow to run the Arduino CLI from [Alfred](https://www.alfredapp.com).
+
+![Screenshot with a list of boards](images/screenshot.png)
+
+This project has been written as the companion example for the post https://zmoog.dev/post/alfred-workflow on my [personal website](https://zmoog.dev).