Need documentation on Crates.io.

[jordanmack]

There is no documentation for the Molecule crates.

https://crates.io/crates/molecule
https://crates.io/crates/molecule-codegen
https://crates.io/crates/moleculec

Particularly for the first one, it needs basic usage instructions at a bare minimum. Trying to use the Molecule crate in a Capsule project will fail unless it is added with default-features=false. This needs to be specified.

[dependencies]
ckb-std = "0.14.0"
molecule = { version = "0.8.0", default-features = false }

[zhangsoledad]

#95