bpo-35584: Clarify role of caret in a class class (GH-11946)

https://bugs.python.org/issue35584

Doc/howto/regex.rst

@@ -96,8 +96,9 @@ special nature.
 
 You can match the characters not listed within the class by :dfn:`complementing`
 the set.  This is indicated by including a ``'^'`` as the first character of the
-class; ``'^'`` outside a character class will simply match the ``'^'``
-character.  For example, ``[^5]`` will match any character except ``'5'``.
+class. For example, ``[^5]`` will match any character except ``'5'``.  If the
+caret appears elsewhere in a character class, it does not have special meaning.
+For example: ``[5^]`` will match either a ``'5'`` or a ``'^'``.
 
 Perhaps the most important metacharacter is the backslash, ``\``.   As in Python
 string literals, the backslash can be followed by various characters to signal