docs: animated gif

Author: predic8

README.md

@@ -5,6 +5,9 @@
 [![GitHub release](https://img.shields.io/github/release/membrane/service-proxy.svg)](https://github.com/membrane/service-proxy/releases/latest)
 [![Hex.pm](https://img.shields.io/hexpm/l/plug.svg)](https://raw.githubusercontent.com/membrane/api-gateway/master/distribution/router/LICENSE.txt)
 
+
+![API Gateway Demo](docs/images/api-gateway-demo.gif)
+
 Lightweight **API Gateway** for **REST**, **GraphQL** and **legacy SOAP Web Services**, easily extended with powerful plugins and Java.
 
 Solve even complex custom API requirements with simple configurations.