PageHeader: mark PageHeader as it is signed off from accessibility

[broccolinisoup]

PageHeader is signed-off from accessibility https://github.com/github/primer/issues/1115 - updating the realted docs here.

Changelog

New

Changed

• Update a11yReviewed in the docs.json as true
• Update mdx checklist to reflect the current status

Removed

Rollout strategy

• [ ] Patch release
• [ ] Minor release
• [ ] Major release; if selected, include a written rollout or migration plan
• [x] None; Docs changes

Testing & Reviewing

Merge checklist

• [ ] Added/updated tests
• [ ] Added/updated documentation
• [ ] Added/updated previews (Storybook)
• [ ] Changes are SSR compatible
• [ ] Tested in Chrome
• [ ] Tested in Firefox
• [ ] Tested in Safari
• [ ] Tested in Edge
• [ ] (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[changeset-bot[bot]]

⚠️ No Changeset found

Latest commit: 49a56c234c9506be7d383c34f1d06be983d52337

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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[github-actions[bot]]

size-limit report 📦

Path	Size
packages/react/dist/browser.esm.js	88.49 KB (0%)
packages/react/dist/browser.umd.js	88.84 KB (0%)