Provide an easy way to access previous versions docs

[adesurirey]

React Query is moving very fast and I cannot afford to always upgrade to the latest version.

Pains:

• Currently, accessing a previous version documentation can only be done on github and is not trivial
• When on the website, there is no way to know wich documentation version I'm looking at

Solution:

• Add a versions dropdown on the website navbar

[TkDodo]

https://react-query-v2.tanstack.com/docs/overview

It’s right there with a link on the start page:

yes, the search is not working. There are at least 3 closes issues about it :)