Fix markup to not add parens to the "hashlib.md5" constructor when the object is…

Fix markup to not add parens to the "hashlib.md5" constructor when the object is meant, not the call.

Doc/library/hmac.rst

@@ -19,7 +19,7 @@ This module implements the HMAC algorithm as described by :rfc:`2104`.
    Return a new hmac object.  *key* is a bytes object giving the secret key.  If
    *msg* is present, the method call ``update(msg)`` is made.  *digestmod* is
    the digest constructor or module for the HMAC object to use. It defaults to
-   the :func:`hashlib.md5` constructor.
+   the :data:`hashlib.md5` constructor.
 
 
 An HMAC object has the following methods: