add first-steps summary to reiterate on commands

[WebFreak001]

replaces / fix #52

[netlify[bot]]

✅ Deploy Preview for dub-registry ready!

Name	Link
🔨 Latest commit	bdd4d3ee2d93d34bb91ced2c5ce541288125b15f
🔍 Latest deploy log	https://app.netlify.com/sites/dub-registry/deploys/655f2f2d56f8710008d5dbe3
😎 Deploy Preview	https://deploy-preview-80--dub-registry.netlify.app/getting-started/first-steps
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.