These three components have shipped since llms.txt was added in shadcn-ui#8460
and were never listed. LLMs hitting /llms.txt get a catalog missing
them:

- Direction: text direction provider (RTL support)
- Native Select: styled native HTML select
- Sonner: opinionated toast (Toast uses it under the hood but Sonner
  is also exposed as its own component at /docs/components/sonner)

Noticed while working on shadcn-ui#9484.

llms.txt was added in shadcn-ui#8460 and hasn't kept up with the docs tree.
Audited every section against apps/v4/content/docs and fixed the
drift in one pass.

Removed:
- About (/docs/about) returns 404, the mdx file doesn't exist

Added to Overview:
- Skills (/docs/skills)
- Directory (/docs/directory)

Added whole RTL section (new since shadcn-ui#8460):
- RTL (/docs/rtl)
- RTL - Next.js
- RTL - Vite
- RTL - TanStack Start

Added to Components:
- Direction (Misc)
- Native Select (Form & Input, after Select)
- Sonner (Feedback & Status, after Toast, since Sonner has its own
  docs page even though Toast already uses it under the hood)

Added to Registry:
- Namespaces
- Add a Registry (open source registry index)
- Open in v0 integration
- registry.json schema docs
- registry-item.json spec docs

Descriptions match the short curated style of the rest of the file.
Noticed while working on shadcn-ui#9484.

llms.txt was added in shadcn-ui#8460 and hasn't kept up with the docs tree.
Audited every URL against apps/v4/content/docs and fixed the drift
in one pass.

Removed:
- About (/docs/about): returns 404, no about.mdx exists
- Form (/docs/components/form): points at a phantom. No radix/form.mdx
  exists post-shadcn-ui#9304. URL only resolves because of a redirect in
  next.config.mjs, which lands at /docs/forms. That page is already
  listed as 'Forms Overview' in the ## Forms section, and the real
  form library docs (React Hook Form, TanStack Form, Next.js) are
  listed there too. The Form component entry is a stale duplicate.

Added to Overview:
- Skills (/docs/skills)
- Directory (/docs/directory)

Added whole RTL section (new since shadcn-ui#8460):
- RTL (/docs/rtl)
- RTL - Next.js
- RTL - Vite
- RTL - TanStack Start

Added to Components:
- Direction (Misc)
- Native Select (Form & Input, after Select)
- Sonner (Feedback & Status, after Toast, since Sonner has its own
  docs page even though Toast already uses it under the hood)

Added to Registry:
- Namespaces
- Add a Registry (open source registry index)
- Open in v0 integration
- registry.json schema docs
- registry-item.json spec docs

Descriptions match the short curated style of the rest of the file.
Noticed while working on shadcn-ui#9484.