Add example for loading Swup as ESM import from CDN

[daun]

• Add an example for a module/nomodule loading pattern
• Use the correct ?module URL of Unpkg

Closes #84

[netlify[bot]]

✅ Deploy Preview for splendorous-kataifi-9ae281 ready!

Name	Link
🔨 Latest commit	cf02e0e9b8d5c8b699b2d26571abee3b03c8eca7
🔍 Latest deploy log	https://app.netlify.com/sites/splendorous-kataifi-9ae281/deploys/646e2d26ed69c60008c69c49
😎 Deploy Preview	https://deploy-preview-113--splendorous-kataifi-9ae281.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 settings.