Add YouTube playlist link to Ready to start? section

[tynandebold]

Description

The YouTube link is live and now it's added.

QA notes

View the deployed link and ensure the link opens to the right location.

Checklist

• [ ] Opened this PR as a 'Draft Pull Request' if it is work-in-progress
• [ ] Added tests to cover my changes, where applicable

[netlify[bot]]

✅ Deploy Preview for kedro-website ready!

Name	Link
🔨 Latest commit	7c836ce1dd738acd84305d30dcb38fe0e39d32e1
🔍 Latest deploy log	https://app.netlify.com/sites/kedro-website/deploys/6581885e9795cd0007a00e86
😎 Deploy Preview	https://deploy-preview-181--kedro-website.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.
Lighthouse	1 paths audited Performance: 75 (🔴 down 3 from production) Accessibility: 91 (no change from production) Best Practices: 83 (no change from production) SEO: 92 (no change from production) PWA: - View the detailed breakdown and full score reports

---

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