Change tag variable name to improve clarity.

See KMAC256 for corresponding change.

Author: jelaiw

Doc/src/hash/kmac128.rst

@@ -22,13 +22,13 @@ And this is an example showing how to validate the KMAC128 tag::
     >>> from Crypto.Hash import KMAC128
     >>>
     >>> # We have received a message 'msg' together
-    >>> # with its MAC 'mac'
+    >>> # with its MAC 'mac_tag'
     >>>
     >>> secret = b'Sixteen byte key'
     >>> mac = KMAC128.new(key=secret, mac_len=16)
     >>> mac.update(msg)
     >>> try:
-    >>>   mac.verify(mac)
+    >>>   mac.verify(mac_tag)
     >>>   print("The message '%s' is authentic" % msg)
     >>> except ValueError:
     >>>   print("The message or the key is wrong")