Add preview screenshot to page about the platform

cloud-platform.md

@@ -30,6 +30,10 @@ Further functionality of the first version includes
 * Possibility to access a service via a link
 * Indication of service status
 
+This design preview gives you an idea how the web application will look like:
+
+![Preview of the Cloud Access Layer](./assets/img/screenshots/cloud-platform-preview-small.png)
+
 Later versions will contain more enhanced features like
 * Personal workspace with overview about the personal set of services
 * Possibility to request more specific setup of services