Update use_cookie.rs doc

[JosiahParry]

Update use_cookie doc to explicitly mention that both ssr and axum/actix/spin features are required

[maccesch]

Thanks for trying to improve the docs!

However, that part is already mentioned in the ssr chapter of the book and doesn't apply exclusively to use_cookie.

Also if you write it like this, then there are going to be even more ppl reading that as "enable feature ssr always" which leads to the most common issue ppl have with Leptos-Use.