WIP: Add sub-page support

[kylegach]

What I did

1. Generate docs TOC
   • Use existing toc.js, if available
   • Supports
     • Ordering
     • Different titles for the nav item vs. the page/heading (e.g. Stories vs. How to write stories)
     • Non-routed groups (e.g. Testing > Snapshot testing)
     • Redirects (e.g. the Get started heading leads to the Install page instead of an index)
   • See test mocks for usage examples
2. Add sub-page support
   • Supports
     • Regular sub-pages (e.g. /writing-stories/args/api)
       • Display as tabs on the index (Guide) page
       • Do not display in the sidebar nav
     • Nested sub-pages (e.g. /writing-stories/args/api/nested)
       • Maintain the active tab of their parent sub-page
       • Do not display in the sidebar nav
   • See test mocks for usage examples

How to test

TK

[netlify[bot]]

✅ Deploy Preview for storybook-frontpage ready!

Name	Link
🔨 Latest commit	f7387e250b5b6d7bc7de0c2a5569314e3b4ea09d
🔍 Latest deploy log	https://app.netlify.com/sites/storybook-frontpage/deploys/657fc0568f0c1d0008f06e1b
😎 Deploy Preview	https://deploy-preview-649--storybook-frontpage.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.

[socket-security[bot]]

New dependencies detected. Learn more about Socket for GitHub ↗︎

Packages	Version	New capabilities	Transitives	Size	Publisher
gray-matter	4.0.3	None	+0	38.6 kB	rmassaioli