add release badge

Author: Philipp Molitor

README.md

@@ -3,6 +3,7 @@
 <p align="center">
 
 <img src="https://github.com/PhilippMolitor/react-unity-renderer/actions/workflows/ci-dev.yaml/badge.svg?branch=dev">
+<img src="https://github.com/PhilippMolitor/react-unity-renderer/actions/workflows/release-npmjs.yaml/badge.svg?event=release">
 <img src="https://img.shields.io/npm/l/react-unity-renderer">
 <img src="https://img.shields.io/npm/dw/react-unity-renderer">
 <img src="https://img.shields.io/github/stars/PhilippMolitor/react-unity-renderer">