bpo-42236: Enhance init and encoding documentation (GH-23109)

Enhance the documentation of the Python startup, filesystem encoding
and error handling, locale encoding. Add a new "Python UTF-8 Mode"
section.

* Add "locale encoding" and "filesystem encoding and error handler"
  to the glossary
* Remove documentation from Include/cpython/initconfig.h: move it to
  Doc/c-api/init_config.rst.
* Doc/c-api/init_config.rst:

  * Document command line options and environment variables
  * Document default values.

* Add a new "Python UTF-8 Mode" section in Doc/library/os.rst.
* Add warnings to Py_DecodeLocale() and Py_EncodeLocale() docs.
* Document how Python selects the filesystem encoding and error
  handler at a single place: PyConfig.filesystem_encoding and
  PyConfig.filesystem_errors.
* PyConfig: move orig_argv member at the right place.

1 files changed, 1 insertions, 0 deletions

diff --git a/Python/initconfig.c b/Python/initconfig.c
index d0ff888..7bb28ed 100644
--- a/Python/initconfig.c
+++ b/Python/initconfig.c
@@ -543,6 +543,7 @@ _Py_SetArgcArgv(Py_ssize_t argc, wchar_t * const *argv)
 }
 
 
+// _PyConfig_Write() calls _Py_SetArgcArgv() with PyConfig.orig_argv.
 void
 Py_GetArgcArgv(int *argc, wchar_t ***argv)
 {