docs: added preview image of the CLI

Author: Peter Schwips

README.md

@@ -3,6 +3,8 @@
 Unofficial CLI for SAP Datasphere that automates various tasks such as managing
 analytical models, remote tables, task chains and views.
 
+![Preview of the CLI](./static/cli.png)
+
 ## 📋 Table of Contents
 
 - [Overview](#-overview)