Do C-API docs need an update? For instance, dev/internals.code-explanations.rst
mentions PyArray_Descr->f, but looking at the implementation in ndarraytypes.h
I don't see an f attribute.

Also, the first "Iteration example" under c-api/iterator.rst uses code which
to me it seems not valid anymore:

    PyArray_NonzeroFunc* nonzero = PyArray_DESCR(self)->f->nonzero;

and if I'm not mistaken, the modern way to do this is:

    PyArray_NonzeroFunc* nonzero = PyDataType_GetArrFuncs(PyArray_DESCR(self))->nonzero;

But I also didn't manage to make g++ happy even after a #include "numpy/npy_2_compat.h", so I'm probably missing something.

I'm not sure where else these instances occur, still trying to wrap my head around
the C-API.

Also, it would be really nice if we could have info on which includes are necessary
for which part of the docs, and maybe some basic minimal examples which can be
compiled on their own. Another nice thing to have would be to have examples to deal
with the actual values stored in the arrays instead of always using functions
attached to PyArray_Descr.

This is all in the context of #26018