bpo-17050: Remove documentation on argparse.REMAINDER (GH-18661)

Closes [Issue 17050]() by removing argparse.REMAINDER from the documentation, as discussed on the issue.

Automerge-Triggered-By: @rhettinger

Doc/library/argparse.rst

@@ -961,19 +961,6 @@ values are:
      usage: PROG [-h] foo [foo ...]
      PROG: error: the following arguments are required: foo
 
-.. _`argparse.REMAINDER`:
-
-* ``argparse.REMAINDER``.  All the remaining command-line arguments are gathered
-  into a list.  This is commonly useful for command line utilities that dispatch
-  to other command line utilities::
-
-     >>> parser = argparse.ArgumentParser(prog='PROG')
-     >>> parser.add_argument('--foo')
-     >>> parser.add_argument('command')
-     >>> parser.add_argument('args', nargs=argparse.REMAINDER)
-     >>> print(parser.parse_args('--foo B cmd --arg1 XX ZZ'.split()))
-     Namespace(args=['--arg1', 'XX', 'ZZ'], command='cmd', foo='B')
-
 If the ``nargs`` keyword argument is not provided, the number of arguments consumed
 is determined by the action_.  Generally this means a single command-line argument
 will be consumed and a single item (not a list) will be produced.