Relation to nightly Rust

Nadie ha tomado este issue todavía.

Thanks for building these crates! I am tempted to experiment with them, most likely in PyO3's CI initially - we have a [`pyo3-ffi-check`](https://github.com/PyO3/pyo3/tree/20246a895718baa603f836b187b498cedc6941ca/pyo3-ffi-check) helper which compares our hand-maintained FFI to bindgen (because reasons).

Currently has a ton of hacks where I build docs html and parse that, which is painful plus has shortcomings like case-insensitive filesystems meaning I can't easily check the difference between e.g. `Py_INCREF` and `Py_IncRef` symbols.

I understand that the rustdoc JSON is still not stable. Do these crates automate the process of pinning / selecting the right nightly toolchain to get "stable" rustdoc JSON processing?

Comienza con el helper pyo3-ffi-check enlazado en el issue y revisa cómo depende actualmente del HTML de documentación generado. Después, inspecciona el rustdoc JSON de los crates y los puntos de entrada de nightly-toolchain para determinar si se admite fijar o seleccionar un nightly compatible. Se considera terminado documentar la capacidad actual y, si no existe, definir el comportamiento de automatización y compatibilidad requerido.

Escrito por el modelo de indexación a partir del texto del issue.