Add --save-hybrid mAP warning (#9050)

* Add `--save-hybrid` mAP warning

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

* Update val.py

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

val.py

@@ -365,6 +365,8 @@ def main(opt):
     if opt.task in ('train', 'val', 'test'):  # run normally
         if opt.conf_thres > 0.001:  # https://github.com/ultralytics/yolov5/issues/1466
             LOGGER.info(f'WARNING: confidence threshold {opt.conf_thres} > 0.001 produces invalid results ⚠️')
+        if opt.save_hybrid:
+            LOGGER.info('WARNING: --save-hybrid will return high mAP from hybrid labels, not from predictions alone ⚠️')
         run(**vars(opt))
 
     else: