Fix redundant declaration of cmd2.Cmd.__init__ method

Author: kotfu

docs/features/history.rst

@@ -11,9 +11,7 @@ For Developers
 - reference the public code structures we use to store history
 
 ``cmd2`` adds the option of making this history persistent via optional
-arguments to ``cmd2.Cmd.__init__()``:
-
-.. automethod:: cmd2.Cmd.__init__
+arguments to :meth:`cmd2.Cmd.__init__`.
 
 
 For Users