gh-141004: Document built-in iterator types in the C API (GH-141006)
Adds documentation for each of the following:
- PyEnum_Type
- PyFilter_Type
- PyMap_Type
- PyReversed_Type
- PyZip_Type
In addition, PyRange_Type and PyRange_Check are also documented.
(cherry picked from commit 1697cb5710)
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
I think that none of these API calls can fail, but only few of them are
documented as such. Add the sentence "This function always succeeds" (which is
the same already used e.g. by PyNumber_Check) to all of them.