Update comment

tool/ompt_callbacks.cpp

@@ -438,7 +438,7 @@ ompt_callback_task_schedule_action(
 #if LOG
     printf("%" PRIu64 ": ompt_event_task_begin: task_id=%" PRIu64 ", status=%i, deps: %p\n", thread_id, new_task->id, prior_task_status, new_task->deps);
 #endif
-    /* This is code for implicit task begin.
+    /* This is code for explicit task begin.
     */
     kaapi_ompt_thread_info_t* koti = &__kaapi_oth_info[thread_id];
     kaapi_tracelib_thread_switchstate(koti->kproc);