Merge "Update LANE_KEEP_ASSIST_ENABLED documentation in HAL"

     * This is different from Lane Centering Assist (LCA) which, when activated, applies continuous

     * steering control to keep the vehicle centered in the current lane.

     *

     * In general, LANE_KEEP_ASSIST_ENABLED should always return true or false. If the feature is

     * not available due to some temporary state, such as the vehicle speed being too low or too

     * high, that information must be conveyed through the ErrorState values in the

     * LANE_KEEP_ASSIST_STATE property.

     *

     * This property is defined as read_write, but OEMs have the option to implement it as read

     * only.

     *