Codegen

[uncomputable]

Depends on #54

Add documentation for each jet. The documentation is currently not needed in Simfony itself, so it lives in a subcrate that generates Rust code for https://github.com/uncomputable/simfony-as-rust, a compatibility layer to work on Simfony inside the Rust ecosystem. We can use rustdoc to generate documentation for each jet.

[uncomputable]

Rebased

[apoelstra]

concept ACK but (a) where did this text come from? Can you provide instructions or pointers on how to reproduce it? and (b) can you run cargo +nightly fmt over it?

Unrelatedly, one benefit of the local-CI overhaul I did 2 months ago is that it now detects new crates and runs all the tests on them, including generating a feature matrix, without any intervention from me :).

[uncomputable]

This text cannot be auto generated because it was written by hand. Sources are the tech report, especially for the Elements jets; the Haskell documentation, especially for the libsecp jets; and conversations with @roconnor-blockstream. Truth is, there is no single source of documentation for all jets. I made it here.

[uncomputable]

I ran the code formatter.