[docs] Describe the new subplugintypes object (MDL-83705)

[andrewnicols]

No description provided.

[netlify]

✅ Deploy Preview for moodledevdocs ready!

Name	Link
🔨 Latest commit	a94a6d5
🔍 Latest deploy log	https://app.netlify.com/sites/moodledevdocs/deploys/6760da0b29d6ed00088d6b6f
😎 Deploy Preview	https://deploy-preview-1210--moodledevdocs.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.

[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟠 64	🟢 95	🟢 100	🟢 90	🟢 100	Report
/docs/5.0/apis/commonfiles	🟠 51	🟢 93	🟢 100	🟢 100	🟢 100	Report
/general/development/gettingstarted	🟠 56	🟢 95	🟢 100	🟢 90	🟢 100	Report
/general/releases	🟠 59	🟢 95	🟢 100	🟢 100	🟢 100	Report

[andrewnicols]

@HuongNV13 this has landed - can you please review this docs change.

[HuongNV13]

Thanks, Andrew
It looks good to me!