Darkmode | html element identifier

[arno-fukuda]

Describe the problem

Docusaurus and other frameworks implement darkmode by using data-theme=dark/light in the html tag.

The build-in darkmode for docsearch is dependent on this element.

Other popular frameworks like nextjs with next-themes set class='dark' on the html tag.

Component libraries like MUI might set something completely different.

Describe the solution

Pass a prop to docsearch, telling which identifier in the tag should be used to determine darkmode.

[Sid-80]

I am willing to work on this issue!