Added screenshots to pubspec.yaml

@@ -3,6 +3,26 @@ description: A universal barcode and QR code scanner for Flutter based on MLKit.
 version: 3.5.6
 repository: https://github.com/juliansteenbakker/mobile_scanner
 
+screenshots:
+- description: 'Flutter Demo Home Page'
+  path: example\screenshots\flutter_01.png
+- description: 'Mobile Scanner with List controller'
+  path: example\screenshots\flutter_02.png
+- description: 'Mobile Scanner with controller'
+  path: example\screenshots\flutter_03.png
+- description: 'Mobile Scanner with scan window'
+  path: example\screenshots\flutter_04.png
+- description: 'Mobile Scanner with controller (returning image)'
+  path: example\screenshots\flutter_05.png
+- description: 'Mobile Scanner without controller'
+  path: example\screenshots\flutter_06.png
+- description: 'Mobile Scanner with zoom slider'
+  path: example\screenshots\flutter_07.png
+- description: 'Mobile Scanner pageView'
+  path: example\screenshots\flutter_08.png
+- description: 'Mobile Scanner with overlay'
+  path: example\screenshots\flutter_09.png
+
 environment:
   sdk: ">=2.17.0 <4.0.0"
   flutter: ">=3.0.0"