bpo-39976: Add **other_popen_kwargs to subprocess docs (GH-20145)

Patch by Zackery Spytz.

Author: ZackerySpytz

Doc/library/subprocess.rst

@@ -40,7 +40,7 @@ compatibility with older versions, see the :ref:`call-function-trio` section.
 .. function:: run(args, *, stdin=None, input=None, stdout=None, stderr=None,\
  capture_output=False, shell=False, cwd=None, timeout=None, \
  check=False, encoding=None, errors=None, text=None, env=None, \
- universal_newlines=None)
+ universal_newlines=None, **other_popen_kwargs)
 
  Run the command described by *args*. Wait for command to complete, then
  return a :class:`CompletedProcess` instance.
@@ -1085,7 +1085,8 @@ Prior to Python 3.5, these three functions comprised the high level API to
 subprocess. You can now use :func:`run` in many cases, but lots of existing code
 calls these functions.
 
-.. function:: call(args, *, stdin=None, stdout=None, stderr=None, shell=False, cwd=None, timeout=None)
+.. function:: call(args, *, stdin=None, stdout=None, stderr=None, \
+ shell=False, cwd=None, timeout=None, **other_popen_kwargs)
 
  Run the command described by *args*. Wait for command to complete, then
  return the :attr:`~Popen.returncode` attribute.
@@ -1111,7 +1112,9 @@ calls these functions.
  .. versionchanged:: 3.3
  *timeout* was added.
 
-.. function:: check_call(args, *, stdin=None, stdout=None, stderr=None, shell=False, cwd=None, timeout=None)
+.. function:: check_call(args, *, stdin=None, stdout=None, stderr=None, \
+ shell=False, cwd=None, timeout=None, \
+ **other_popen_kwargs)
 
  Run command with arguments. Wait for command to complete. If the return
  code was zero then return, otherwise raise :exc:`CalledProcessError`. The
@@ -1142,7 +1145,8 @@ calls these functions.
 
 .. function:: check_output(args, *, stdin=None, stderr=None, shell=False, \
  cwd=None, encoding=None, errors=None, \
- universal_newlines=None, timeout=None, text=None)
+ universal_newlines=None, timeout=None, text=None, \
+ **other_popen_kwargs)
 
  Run command with arguments and return its output.