docs: fix scroll position restoration when navigating back/forward

[reidbarber]

We need to handle this manually since we're using the scrollable container instead of the window.

✅ 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:

Verify that scroll position is restored when navigating back/forward in the browser. Also verify that scroll positions are still accurate for hash links.

🧢 Your Project: