Studio: Add WordPress Playground link in the About Studio window

[katinthehatsite]

Closes https://github.com/Automattic/dotcom-forge/issues/7614

Proposed Changes

This PR adds the link to WordPress Playground: http://w.org/playground to the About Studio window.

Before	After

I used the wording from the issue linked above and the design suggestion from the Slack thread mentioned there. Happy to adjust based on the feedback.

Testing Instructions

• Pull the changes from this branch
• Start the app with nvm use && npm install && npm start
• Click on the app
• Click on Electron > About Studio menu option in the top bar
• Confirm that you see the link to WordPress Playground and clicking the link brings you to http://w.org/playground

Pre-merge Checklist

• [ ] Have you checked for TypeScript, React or other console errors?