chore: add the codspeed badge to the readme

Author: art049

README.md

@@ -6,6 +6,7 @@ Node.js libraries to create CodSpeed benchmarks
 [![CI](https://github.com/CodSpeedHQ/codspeed-node/actions/workflows/ci.yml/badge.svg)](https://github.com/CodSpeedHQ/codspeed-node/actions/workflows/ci.yml)
 [![npm (scoped)](https://img.shields.io/npm/v/@codspeed/core)](https://www.npmjs.com/org/codspeed)
 [![Discord](https://img.shields.io/badge/chat%20on-discord-7289da.svg)](https://discord.com/invite/MxpaCfKSqF)
+[![CodSpeed Badge](https://img.shields.io/endpoint?url=https://codspeed.io/badge.json)](https://codspeed.io/CodSpeedHQ/codspeed-node)
 
 </div>