What problem does this address?

The theme.json Version 2 living reference does not have a prominent place in the search results for "theme.json" As this is the most important theme.json related page in this handbook the page should be adjusted to move it up to as close to the top of that search as possible.

What is your proposed solution?

Adjust page title and possibly introductory paragraph to include better keywords for search as well as to make it clear that this page is related to theme.json.