[4.x] Document the InitializeTenancyByRequestData payload priority

[lukinovec]

In this part of the docs, add a note that says that if the request has multiple payload types (e.g., the request has both the 'X-Tenant' header and cookie), the first type will get used. The priority of the types is header > query parameter > cookie.

https://github.com/tenancy-for-laravel/v4/pull/3#discussion_r1181373786