Replaced old description

core/net/rpl/rpl.h

@@ -160,8 +160,7 @@ typedef struct rpl_parent rpl_parent_t;
  *
  *  Updates the metric container for outgoing DIOs in a certain DAG.
  *  If the objective function of the DAG does not use metric containers, 
- *  the function returns 0. If the metric container has been filled, the 
- *  function returns 1.
+ *  the function should set the object type to RPL_DAG_MC_NONE.
  */
 struct rpl_of {
   void (*reset)(struct rpl_dag *);