Allow installing @gradio/client via cdn

[abidlabs]

It'd be really nice if users install the gradio js client via a cdn in the browser rather than only through npm. Perhaps this is already possible in which we case we should add to the documentation: https://www.gradio.app/guides/getting-started-with-the-js-client

[hannahblair]

Already doable via jsdelivr per @pngwn's comment but let's add it to the docs as part of this issue!