fixed typo in comment

dlib/svm/structural_svm_object_detection_problem.h

@@ -345,7 +345,7 @@ namespace dlib
                 // if hit truth rect
                 if (truth_match > match_eps)
                 {
-                    // if this is the first time we have seen a detect which hit truth_object_detections[truth.second]
+                    // if this is the first time we have seen a detect which hit truth_object_detections[idx][truth.second]
                     const double score = dets[i].first - thresh;
                     if (hit_truth_table[truth.second] == false)
                     {