Minor doc improvement (GH-10341)

Change "star-operator" to "* operator".
(cherry picked from commit dfd775a0b1)

Co-authored-by: Andre Delfino <adelfino@gmail.com>

Doc/library/collections.rst

@@ -959,7 +959,7 @@ function:
     >>> getattr(p, 'x')
     11
 
-To convert a dictionary to a named tuple, use the double-star-operator
+To convert a dictionary to a named tuple, use the ``**`` operator
 (as described in :ref:`tut-unpacking-arguments`):
 
     >>> d = {'x': 11, 'y': 22}

Doc/tutorial/controlflow.rst

@@ -560,7 +560,7 @@ The reverse situation occurs when the arguments are already in a list or tuple
 but need to be unpacked for a function call requiring separate positional
 arguments.  For instance, the built-in :func:`range` function expects separate
 *start* and *stop* arguments.  If they are not available separately, write the
-function call with the  ``*``\ -operator to unpack the arguments out of a list
+function call with the  ``*`` operator to unpack the arguments out of a list
 or tuple::
 
    >>> list(range(3, 6))            # normal call with separate arguments
@@ -573,7 +573,7 @@ or tuple::
    single: **; in function calls
 
 In the same fashion, dictionaries can deliver keyword arguments with the
-``**``\ -operator::
+``**`` operator::
 
    >>> def parrot(voltage, state='a stiff', action='voom'):
    ...     print("-- This parrot wouldn't", action, end=' ')