Add screenshots section to README

Added a new section for screenshots and relevant images.

Author: dido18

README.md

@@ -10,6 +10,7 @@ Accessible from any device via a browser, it makes coding, electronics, and AI h
 ![Scratch for Arduion UNO Q](./doc/blink.png)
 
 <img src="./doc/blink.gif" alt="Blink matrix" width="300"/>
+
 ## Installation
 
 - Open the Arduino App lab and connect to your UNO Q board.
@@ -24,6 +25,17 @@ curl -sSL https://raw.githubusercontent.com/dido18/scratch-arduino-app/main/inst
 
 NOTE: the `https` is needed by the `getUserMedia()` method for security reason.
 
+## Screenshots
+
+Add the extensions for Arduino UNO Q.
+![Scratch UNO Q extensions](./doc/extensions.png)
+
+Use the matrix block to control the LED matrix.
+![Scratch Matrix](./doc/matrix.png)
+
+Use the Modulino blocks to control the Modulino.
+![Scratch Modulino](./doc/modulino.png)
+
 ## Local development
 
 - `task scratch:init`