Replace the demo link of the Gutenberg Storybook in Docs

[igorradovanov]

Description

I've replaced the Gutenberg Storybook URL with the correct one. The current one resolves to 404.

How has this been tested?

I've confirmed that the page is resolving properly and without a 404 error.

Screenshots

Types of changes

Url path change.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR.

[ajitbohra]

Thank You 👍

[github-actions]

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Kudos!