docs: Add comparison page

[Zamiell]

I think it would be useful to have a comprehensive page comparing Zod, TypeBox, and ArkType, since they all are similar projects, i.e. creating run-time types. It would be nice to have the pros and cons of each solution, and where they differ, and the best use cases for each of them, or something along those lines.

Zod in particular seems to be the most popular solution right now, so I think a page like this helps adoption.

(Also, maybe we should also cover Valibot, which is similar to Zod. But not sure how much traction Valibot is getting lately.)