Clarify that root specifies download target folder (#434)

torchvision/datasets/cifar.py

@@ -18,7 +18,7 @@ class CIFAR10(data.Dataset):
 
     Args:
         root (string): Root directory of dataset where directory
-            ``cifar-10-batches-py`` exists.
+            ``cifar-10-batches-py`` exists or will be saved to if download is set to True.
         train (bool, optional): If True, creates dataset from training set, otherwise
             creates from test set.
         transform (callable, optional): A function/transform that  takes in an PIL image