Improve the docs for Rentals#search endpoint

[Azdaroth]

There are few problems with the current docs

• fees under price_details contain rentals_fee_id, but it is not documented and not present in example payload, this is a very important part, so needs to be fixed. Otherwise it's impossible to reuse data from the payload for creating a booking with bookings fees.
• The docs don't say that fees under price_details contain id (which is present in the example payload), this id is the id of the fee.
• The docs say that fees under price_details are "The required Rental fees to be booked with the Rental." - these are NOT rentals fees! They are actually required fees to be booked with booking, so in that sense these are kind of booking fees (thet contain times booked, price etc., so they are not exactly fees, this makes them closer to bookings fee). I would rather desribe it as details of the bookings fees required to be booked with the rental.