Better documentation of the features offered by blitz auth

### What do you want and why?
Reading and searching the documentation, it is unclear to me wether Blitz offers a built-in way to verify emails on sign up. It would be great if this was documented in the Overview page of the auth section if this is offered, or if there was a page in the docs about how to set it up, as this seems like something almost every app needs.

I've found a [2fa passport strategy](https://www.passportjs.org/packages/passport-2fa-totp/) and think this would be a good addition to the docs as well.

### Additional context
I would like to contribute the docs pages. But I am missing the information regarding the email verification bit, and am not quite sure if a 2fa tutorial is supposed to be in the docs, or better suited for a (personal) blog.

Start with the auth section's Overview page and existing auth documentation to determine whether email verification is built in. Confirm with maintainers whether the linked Passport 2FA strategy belongs in the docs; done means the supported email-verification setup is clearly documented and any agreed 2FA guidance has an appropriate page.

Written by the indexing model from the issue text.