fix replacement key for deprecated option `display.height`

replacement key for deprecated option `display.height` was set to `display.height` itself. I believe it should be `display.max_rows` instead.

This avoid a weird message in `describe_option()` :

    display.height: [default: 60] [currently: 60]
    : int
            Deprecated.
	    (Deprecated, use `display.height` instead.)

(I spotted it while reading the online doc http://pandas.pydata.org/pandas-docs/dev/basics.html?highlight=display.height#working-with-package-options )