Fixed allow_redirection documentation

Author: kmvanbrunt

docs/features/redirection.rst

@@ -64,6 +64,7 @@ Disabling Redirection
        from cmd2 import Cmd
        class App(Cmd):
            def __init__(self):
+               super().__init__()
                self.allow_redirection = False
 
    cmd2's parser will still treat the ``>``, ``>>``, and `|` symbols as output