new migration guide for integrators and exchanges

[netlify[bot]]

✅ Deploy Preview for developer-center ready!

Name	Link
🔨 Latest commit	89995d49e0af72fec5757ef719284e9edb2ea0fc
🔍 Latest deploy log	https://app.netlify.com/sites/developer-center/deploys/671230317d074f00080ef3b9
😎 Deploy Preview	https://deploy-preview-74--developer-center.netlify.app
📱 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.

[onmax]

deployed