`PyConfig.lazy_imports` is missing from the C API configuration docs

[fedonman]

Documentation

lazy_imports is a PUBLIC entry in PYCONFIG_SPEC (Python/initconfig.c:127) and a
member of PyConfig (Include/cpython/initconfig.h:194), so it can be read at runtime.
It is the only one of the 25 PUBLIC options with no entry in
Doc/c-api/init_config.rst, neither in the Configuration Options list nor as a
c:member: of PyConfig.

import ctypes

api = ctypes.pythonapi
api.PyConfig_Get.restype = ctypes.py_object
api.PyConfig_Get.argtypes = [ctypes.c_char_p]

for name in (b"lazy_imports", b"inspect", b"int_max_str_digits"):
    print(name.decode(), "->", api.PyConfig_Get(name))

lazy_imports -> -1
inspect -> False
int_max_str_digits -> 4300

grep -c lazy_imports Doc/c-api/init_config.rst returns 0, while the other two names in
that output are both documented there.

PEP 810 (GH-142351) documented the feature elsewhere: -X lazy_imports,
PYTHON_LAZY_IMPORTS and the C functions in Doc/c-api/import.rst all landed with it.
init_config.rst looks like the file it missed.

The value is a tri-state and that is undocumented too. Python/initconfig.c:1092 says
lazy_imports can be -1 (default) or 1 (on), and that 0 is rejected later.

3.15 has the same gap: the spec entry is there and the doc entry is not.

Linked PRs

• gh-155273: Document PyConfig.lazy_imports in C API config docs #155274
• gh-155273: Document PyConfig.lazy_imports #155281