update REAME

Author: chengshen

README.md

@@ -38,6 +38,14 @@ For DnD benchmark,  we use MixUp additionally:
 python train_mge.py -d prepared_data_path -n num_gpus --dnd
 ```
 
+### Begin testing:
+Download the pretrained checkpoint and use:
+
+```
+python test.py -d prepared_data_path -c checkpoint_path
+```
+The result is **PSNR 39.765**.
+
 
 
 ## Pretrained model

train_mge.py

@@ -23,7 +23,7 @@
 
 def main():
     parser = argparse.ArgumentParser(description="MegEngine NBNet")
-    parser.add_argument("-d", "--data", default="/data/sidd", metavar="DIR", help="path to imagenet dataset")
+    parser.add_argument("-d", "--data", default="/data/sidd", metavar="DIR", help="path to sidd dataset")
     parser.add_argument("--dnd", action='store_true', help="training for dnd benchmark")
     parser.add_argument(
         "-a",