Update link to guide on expressjs.com - #221

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: coverallsapp/github-action@09b709cf6a16e30b0808ba050c7a6e8a5ef13f8d. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/