This direction is wrong, billing email preferences are on the subscriptions tab

### Existing documentation URL(s)

https://developers.cloudflare.com/billing/manage/invoices/#enable-email-invoices-from-cloudflare

### What changes are you suggesting?

I just spent a bunch of time trying to find out where the billing email preferences are because the documentation is wrong. The docs say it's on the "invoices and documents" tab but it is not there at all. The billing email preferences are accessed from a card called Billing Email in the sidebar of the "Subscriptions" tab under Manage Account > Billing.

### Additional information

_No response_