Add remark on the format of the input tensor in dnn_spatialtf

theano/gpuarray/dnn.py

@@ -2974,7 +2974,10 @@ def dnn_spatialtf(img, theta, scale_width=1, scale_height=1, precision=theano.co
     Parameters
     ----------
     img : tensor
-        Images to which the transformations will be applied.
+        Images to which the transformations will be applied. The implementation
+        assumes the tensor is in NCHW format, where N is the number of images,
+        C is the number of color channels, H is the height of the inputs, and
+        W is width of the inputs.
     theta : tensor
         Affine transformation tensor containing one affine transformation
         matrix per image. ``theta`` is usually generated by the localization