Improve Rust Documentation for EVM

[pgebheim]

Goal

Create high-level rust documentation that encompasses the API for the zk-evm implementation.

Tasks

Priority:

• [ ] Add module level documentation to evm/src/lib.rs - High level overview of how to use the evm proving system, link to sub-documentation for interfaces, data structures, and main interface. This content should be able to be used in the main evm README. Check out this example from Paladin
• [ ] Document prover.rs - Code examples of how major API entrypoints. Example from Paladin.
• [ ] Document the major types used within prover.rs during proof generation

Goal:

• [ ] Add documentation with example across the board for all public APIs (modules in the evm/src). Examples should represent test-cases such that examples in the documentation is actionable.

[Nashtare]

@pgebheim does the linked PR satisfy what you had in mind? I'll let you close this or clarify if you want more specific doc