Issue #19934: Document *None* as an acceptable input to Counter.most_common([n])

Doc/library/collections.rst

@@ -268,9 +268,9 @@ For example::
     .. method:: most_common([n])
 
         Return a list of the *n* most common elements and their counts from the
-        most common to the least.  If *n* is not specified, :func:`most_common`
-        returns *all* elements in the counter.  Elements with equal counts are
-        ordered arbitrarily:
+        most common to the least.  If *n* is omitted or ``None``,
+        :func:`most_common` returns *all* elements in the counter.  Elements
+        with equal counts are ordered arbitrarily:
 
             >>> Counter('abracadabra').most_common(3)
             [('a', 5), ('r', 2), ('b', 2)]