Update deposits REST API documentation to show changes when transactions are decoupled from instant & estimated deposits

[Jinksi]

As we decouple transactions from instant (manual) and estimated deposits on the server, this will impact the API from the /deposits/* endpoints.

We need to understand and communicate these changes to consumers/clients of these endpoints.

This issue aims to document these changes via the deposits REST API documentation introduced in #7840.

See project thread: paJDYF-aY6-p2
See discussion on removing estimated deposits: paJDYF-bD7-p2