[docs] [issue9738] Document the encoding of functions bytes arguments of the C API

STINNER Victor <victor.stinner@haypocalc.com> added the comment: #6543 changed the encoding of the filename argument of PyRun_SimpleFileExFlags() (and all functions based on PyRun_SimpleFileExFlags) and c_filename attribute of the compiler (private) structure in Python 3.1.3: use utf-8 in strict mode instead of filesystem encoding with surrogateescape. ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue9738> _______________________________________