Add RAC submenu to homepage and tailwind starter

[reidbarber]

This was removed from #5648 before the last release.

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices

📝 Test Instructions:

Test docs homepage and tailwind starter storybook.

🧢 Your Project:

[rspbot]

Build successful! 🎉

• View the storybook
• View the storybook-17
• View the storybook-16
• View the documentation

[snowystinger]

Can you create a followup task to add a header and section to this example some time?

[rspbot]

Build successful! 🎉

• View the storybook
• View the storybook-17
• View the storybook-16
• View the documentation

[rspbot]

## API Changes

unknown top level export { type: 'any' }
unknown top level export { type: 'any' }
unknown top level export { type: 'any' }
unknown top level export { type: 'any' }
unknown top level export { type: 'any', access: 'private' }
unknown top level export { type: 'any', access: 'private' }
unknown top level export { type: 'any' }
unknown top level export { type: 'any' }
unknown top level export { type: 'any' }
unknown top level export { type: 'any' }
unknown top level export { type: 'identifier', name: 'Column' }
unknown top level export { type: 'identifier', name: 'Column' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown type { type: 'link' }
unknown top level export { type: 'any' }
unknown top level export { type: 'any' }
unknown top level export { type: 'any' }
unknown top level export { type: 'any' }
unknown top level export { type: 'any' }
unknown top level export { type: 'any' }