Clarify the scope and responsibilities of cb-mpc #80
Description
The cb-mpc documentation jumps into technical details quickly, but it is not always clear what the library is meant to handle and what is expected from the application using it.
Developers new to the project may have trouble understanding which parts of the MPC flow are covered by cb-mpc and which parts they need to build themselves. This can slow down onboarding and cause confusion early on.
Proposed Solution
Add a short, plain-language section that explains the role of cb-mpc, its responsibilities, and its boundaries. This should give readers a clear mental model before they dive into deeper technical documentation.