chore: update README.md - screenshot link fixing (#293)

Author: alex-gilin

packages/backend/README.md

@@ -2,7 +2,7 @@
 
 ## Preview
 
-![Form GUI Screenshot](./resources/preview.png)
+![Form GUI Screenshot](https://raw.githubusercontent.com/SAP/code-snippet/master/packages/backend/resources/preview.png)
 
 ## Overview
 
@@ -14,4 +14,4 @@ This package is the VSCode extension for the Code Snippet Tool. It enables:
   - Invoking custom validation logic.
   - Sending user-provided answers back to the respective contribution/plugin.
 
-This architecture supports interactive, extensible code snippet generation in VSCode, combining custom logic with a modern user interface.
+This architecture supports interactive, extensible code snippet generation in VSCode, combining custom logic with a modern user interface.