Fix documentation typo.

        </attr>

        <!-- Specifies the type of layer backing this view. The default value is none.

             Refer to {@link android.view.View#setLayerType(int, android.graphics.Paint)

             Refer to {@link android.view.View#setLayerType(int, android.graphics.Paint)}

             for more information.-->

        <attr name="layerType">

            <!-- Don't use a layer. -->