Fix doc's example (#2601)

offset's 1 dimension should be batch size

torchvision/ops/deform_conv.py

@@ -38,17 +38,17 @@ def deform_conv2d(
 
 
     Examples::
-        >>> input = torch.rand(1, 3, 10, 10)
+        >>> input = torch.rand(4, 3, 10, 10)
         >>> kh, kw = 3, 3
         >>> weight = torch.rand(5, 3, kh, kw)
         >>> # offset should have the same spatial size as the output
         >>> # of the convolution. In this case, for an input of 10, stride of 1
         >>> # and kernel size of 3, without padding, the output size is 8
-        >>> offset = torch.rand(5, 2 * kh * kw, 8, 8)
+        >>> offset = torch.rand(4, 2 * kh * kw, 8, 8)
         >>> out = deform_conv2d(input, offset, weight)
         >>> print(out.shape)
         >>> # returns
-        >>>  torch.Size([1, 5, 8, 8])
+        >>>  torch.Size([4, 5, 8, 8])
     """
 
     out_channels = weight.shape[0]