fix docstring

Author: dsikka

src/deepsparse/image_classification/validation_script.py

@@ -30,6 +30,10 @@
   --image-size, --image_size INTEGER
                                   integer size to evaluate images at (will be
                                   reshaped to square shape)  [default: 224]
+  --batch-size, --batch_size INTEGER
+                                  Test batch size, must divide the dataset
+                                  evenly, else last batch will be dropped
+                                  [default: 1]                                
   --num-cores, --num_cores INTEGER
                                   Number of CPU cores to run deepsparse with,
                                   default is all available