Update Playground JS API tutorial Link

[jdahir0789]

Motivation for the change, related issues

• The WordPress Links and Resources contained a link that redirected to a 404 page.
• This PR fixes the issue by updating the link to the correct working URL.

Implementation details

• Replaced the https://adamadam.blog/2023/04/12/interactive-intro-to-wordpress-playground-public-api/ with the correct working URL https://wordpress.github.io/wordpress-playground/developers/apis/javascript-api/.
• Verified that the updated link resolves properly and points to the intended resource.

Testing Instructions (or ideally a Blueprint)

• Open the modified Links and Resources page.
• Locate the Apps built with WordPress Playground section where the link appears.
• Confirm that it no longer redirects to a 404 and loads the correct resource.

[fellyph]

Thanks @jdahir0789 !