docs(design-system-docs): document Divider for EDS 2.0

[eddiman]

Summary

• Rewrite the Divider docs page for the new next/Divider component (replaces the empty stub)
• Move the page from Data Display to Surfaces, matching the component's Storybook category
• Register a Surfaces category in sidebars.ts

Test plan

• pnpm --filter design-system-docs start and verify the Divider page renders under Surfaces in the sidebar
• Confirm the Storybook iframe loads eds-2-0-beta-surface-divider--introduction
• Sanity-check that the Data Display category no longer lists Divider

Closes #4701

[pomfrida]

@claude review

[claude]

Claude finished @pomfrida's task in 1m 45s —— View job

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Code Review

• Gather context
• Read changed files
• Review Divider component implementation for accuracy
• Post review feedback

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Overall this is a clean, well-structured docs page. The content is accurate against the component implementation. A few observations below.

Verified correct

• Storybook iframe ID — eds-2-0-beta-surface-divider--introduction matches the story title 'EDS 2.0 (beta)/Surface/Divider' with story name Introduction. ✓
• Color token — The Figma section references --eds-color-border-subtle, which matches divider.css:4 (--_color: var(--eds-color-border-subtle)). ✓
• <hr> semantics — The accessibility section correctly describes the implicit role="separator" from the native <hr> element. ✓
• Sidebar placement — The new Surfaces category sits in a logical position in sidebars.ts and is consistent with how Feedback and Navigation categories are structured (no link/overview page). ✓

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Issues

1. sidebar_position: 2 on the only item in the category

divider.md:3 has sidebar_position: 2, but Divider is currently the only item registered in the Surfaces sidebar category. The position doesn't cause a visible bug, but 1 would be semantically correct. Fix this →

2. Outdated WAI-ARIA spec link

divider.md:36 links to the WAI-ARIA 1.1 spec (2017):

https://www.w3.org/TR/2017/REC-wai-aria-1.1-20171214/#separator

The current version is 1.2. Consider updating to:

https://www.w3.org/TR/wai-aria-1.2/#separator

Fix this →

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Suggestions

3. Missing import/usage example

Other EDS 2.0 docs (e.g. chip.md) include a code snippet showing how to import and use the component. The divider page goes straight from the Storybook embed to "When to Use" with no code example. Adding a small Usage section would keep this consistent:

## Usage

```tsx
import { Divider } from '@equinor/eds-core-react/next'

<Divider />

**4. Other Surfaces stub pages not registered (informational)**

`surfaces/accordion.md`, `card.md`, `side_sheet.md`, and `toolbar.md` already exist as stubs but are not added to the new Surfaces sidebar category. This appears intentional (they're empty stubs), but worth being aware of — the next time a Surface component is documented, the author should remember to add it to the `Surfaces` items array in `sidebars.ts`.

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[pomfrida]

Small nits, will approve after 👍

[pomfrida]

Line 8 and 27 is kind of identical - is it needed here?

[pomfrida]

Suggested change

	Dividers follow the [WAI-ARIA separator pattern](https://www.w3.org/TR/2017/REC-wai-aria-1.1-20171214/#separator) and render as a non-interactive `<hr>` element with `role="separator"`.
	Dividers follow the [WAI-ARIA separator pattern](https://www.w3.org/TR/2017/REC-wai-aria-1.1-20171214/#separator) and renders as a native `<hr>`, which has the implicit ARIA role separator.`.