:contains()'s page should have the "… is a jQuery extension" note

[biziclop]

… like :has() has:

Because :has() is a jQuery extension and not part of the CSS specification, queries using :has() cannot take advantage of the performance boost provided by the native DOM querySelectorAll() method. For better performance in modern browsers, use $( "your-pure-css-selector" ).has( selector/DOMElement ) instead.

https://api.jquery.com/contains-selector/

I attempted a pull request here:

https://github.com/jquery/api.jquery.com/pull/1211