Update outdated infor about client versions

[frant-hartm]

The correct state is

• 3.6+ clients can connect to 3.6+ members, but not to 4.x or 5.x
• 4.x and 5.x clients can connect to 4.x and 5.x members

I am not sure we want to talk about 3.x at all here so simple update should be fine.

[netlify[bot]]

✅ Deploy Preview for hardcore-allen-f5257d ready!

Name	Link
🔨 Latest commit	b3a997ac8c519ed42fd488dd0cbd2c9d59508680
🔍 Latest deploy log	https://app.netlify.com/sites/hardcore-allen-f5257d/deploys/66431b17a7a0970008cf2166
😎 Deploy Preview	https://deploy-preview-1111--hardcore-allen-f5257d.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.