* Remove read-only options:
* "module_search_paths_set": not useful, always true.
* "pythonpath_env": get os.environ['PYTHONPATH'] directly.
* "sys_path_0": only make sense during Python initialization.
* "_install_importlib", "_init_main", "_is_python_build": private
options which only make sense during Python initialization.
* Fix related sys API for base_executable and exec_prefix.
* legacy_windows_fs_encoding is Windows only.
* Fix sorting.
* Remove string types other than UTF-8.
* Exclude the API from the limited C API.
* Remove the explicit preconfiguration.
* Remove the rationale about the limited C API / stable ABI.
* PEP 741: Add sys.get_config_names()
* Add sys.get_config_names() function.
* Add PyInitConfig_HasOption() function.
* Remove Py_ExitWithInitConfig() function.
* Add "Fully remove the preinitialization" section.
* Mention when the caller must hold the GIL.
* Add example increasing an initialization configuration option.
* "Usage of the stable ABI" section: add more quotes.
* Document that options side effects are not taken in
account by PyInitConfig_Set*() functions.
* Add "Spawnw process" section.
* Add Cython rationale.
* Add myself as PEP 741 code owner.