[3.11] [doc] Make subprocess.wait documentation more precise (GH-98700) (#112154)

[doc] Make subprocess.wait documentation more precise (GH-98700)

[doc] Make subprocess.wait doc more precise

An active loop is only used when the `timeout` parameter is used on
POSIX.

When no timeout is used, the code calls `os.waitpid` internally (which puts
the process on a sleep status). On Windows, the internal Windows API
call accepts a timeout parameter, so that is delegated to the OS.
(cherry picked from commit 81ab0e8a4add53035c87b040afda6d554cace528)

Co-authored-by: Luis Pedro Coelho <luis@luispedro.org>