bpo-6559: Update _posixsubprocess.fork_exec doc (GH-16283)

It did not list the argument added in d4cc7bf9.


https://bugs.python.org/issue6559



Automerge-Triggered-By: @gpshead

Modules/_posixsubprocess.c

@@ -900,19 +900,22 @@ cleanup:
 
 
 PyDoc_STRVAR(subprocess_fork_exec_doc,
-"fork_exec(args, executable_list, close_fds, cwd, env,\n\
+"fork_exec(args, executable_list, close_fds, pass_fds, cwd, env,\n\
           p2cread, p2cwrite, c2pread, c2pwrite,\n\
           errread, errwrite, errpipe_read, errpipe_write,\n\
           restore_signals, call_setsid,\n\
-          call_setgid, gid, groups_size, gids,\n\
-          call_setuid, uid,\n\
+          gid, groups_list, uid,\n\
           preexec_fn)\n\
 \n\
 Forks a child process, closes parent file descriptors as appropriate in the\n\
 child and dups the few that are needed before calling exec() in the child\n\
 process.\n\
 \n\
-The preexec_fn, if supplied, will be called immediately before exec.\n\
+If close_fds is true, close file descriptors 3 and higher, except those listed\n\
+in the sorted tuple pass_fds.\n\
+\n\
+The preexec_fn, if supplied, will be called immediately before closing file\n\
+descriptors and exec.\n\
 WARNING: preexec_fn is NOT SAFE if your application uses threads.\n\
          It may trigger infrequent, difficult to debug deadlocks.\n\
 \n\