Storybook: Fix table markup in Design Language - Radius docs

[tyxla]

What?

Fixes a warning in the Design Language - Radius docs.

Why?

Just fixing a warning in the Storybook design system docs.

Found while working on #67574.

How?

We're adding thead and tbody sections, respectively.

Testing Instructions

• Open the Design Language - Radius page in Storybook: http://localhost:50240/?path=/docs/foundations-design-language-radius--page
• Verify that there is no DOM warning in the console.

Testing Instructions for Keyboard

Same

Screenshots or screencast

Error before this PR:

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: tyxla <tyxla@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[github-actions]

Flaky tests detected in 5f76024.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/12197025229
📝 Reported issues:

• [Flaky Test] submenu click on the arrow interactions #61884 in /test/e2e/specs/editor/blocks/navigation-frontend-interactivity.spec.js