Add helpful logging

dlib/dnn/trainer.h

@@ -1047,7 +1047,10 @@ namespace dlib
                     // might be better off giving up at this learning rate, and trying a
                     // lower one instead.
                     if (prob_loss_increasing_thresh >= prob_loss_increasing_thresh_max_value)
+                    {
+                        std::cout << "(and while at it, also shrinking the learning rate)" << std::endl;
                         learning_rate = learning_rate_shrink * learning_rate;
+                    }
                 }
                 else
                 {