[INTERNAL] Add message for v3 deprecation

Author: d3xter666

README.md

@@ -9,6 +9,12 @@
 [![npm Package Version](https://badge.fury.io/js/%40ui5%2Fserver.svg)](https://www.npmjs.com/package/@ui5/server)
 [![Coverage Status](https://coveralls.io/repos/github/SAP/ui5-server/badge.svg)](https://coveralls.io/github/SAP/ui5-server)
 
+> [UI5 CLI v4](https://ui5.github.io/cli/v4) is the latest and stable version 🎉
+>
+> [UI5 CLI v2](https://ui5.github.io/cli/v2) and [UI5 CLI v3](https://ui5.github.io/cli/v3) have been deprecated 🚫  
+>
+> Please migrate your projects to [UI5 CLI v4](https://ui5.github.io/cli/stable/updates/migrate-v4/)!
+
 ## Documentation
 UI5 Server documentation can be found here: [ui5.github.io/cli](https://ui5.github.io/cli/v3/pages/Server/)