Fix a variable name reference in Activity docs.

    /**

     * This method is called after {@link #onStart} when the activity is

     * being re-initialized from a previously saved state, given here in

     * <var>state</var>.  Most implementations will simply use {@link #onCreate}

     * <var>savedInstanceState</var>.  Most implementations will simply use {@link #onCreate}

     * to restore their state, but it is sometimes convenient to do it here

     * after all of the initialization has been done or to allow subclasses to

     * decide whether to use your default implementation.  The default