Update products API to add the search_fields parameter

[staskus]

Adds documentation for the changes on the products endpoint introduced in:
woocommerce/woocommerce#59450

Testing steps

• Run the build script found in the root of this repo: ./build.sh
• Find the build directory created by the script, and the index.html file within. Load that file in your web browser.
• Click on the Products > List all products item in the left-side menu and make sure the search_fields parameter is documented.

⚠️ We should not merge this until 10.1.0 is released ⚠️