Update functional.py (pytorch#1298)

Author: shubhamjain0594

torch/nn/functional.py

@@ -463,7 +463,7 @@ def nll_loss(input, target, weight=None, size_average=True):
     See :class:`~torch.nn.NLLLoss` for details.
 
     Args:
-        input: :math:`(N, C)` where `C = number of classes`
+        input: :math:`(N, C)` where `C = number of classes` or `(N, C, H, W)` in case of 2D - Loss
         target: :math:`(N)` where each value is `0 <= targets[i] <= C-1`
         weight (Variable, optional): a manual rescaling weight given to each
                 class. If given, has to be a Variable of size "nclasses"