Clarify the order of optimized splits

src/lib/reasoners/relation.ml

@@ -158,9 +158,9 @@ let optimizing_split env uf opt_split =
     Rel5.optimizing_split env.r5 uf;
     Rel6.optimizing_split env.r6 uf;
     Rel7.optimizing_split env.r7 uf ]
-(* (* Currently, we optimize one split per call and the below
-   sorting has no effects since the list contains at most one element. *)
-   |> List.fast_sort (fun a b -> a.Th_util.order - b.Th_util.order) *)
+(* Currently, we optimize one split per call of this function. If we
+   support multiple optimizations some day, we'll need to sort the splits
+   in order to process them in the user-defined order. *)
 
 let add env uf r t =
   Options.exec_thread_yield ();