Set expectations around setup effort and learning curve

[acacias-passing]

Overview

For new users, it’s not always clear how much setup or background knowledge is needed to use cb-mpc. A small bit of context up front would make it easier to decide whether the project is a good fit.
Developers may be unsure if cb-mpc can be tried quickly or if it requires a more involved setup and deeper understanding. This uncertainty can make initial evaluation harder than it needs to be.

Proposed Solution

Add a short note near the top of the README that explains what kind of setup to expect and who the library is intended for.