Updated docs to add the error case for torch.multinomial

Summary: Updated docs to add the error condition for torch.multinomial

Test Plan: No change in code

Reviewers:

Subscribers: @drisspg

Tasks:

Tags:

torch/_torch_docs.py

@@ -7873,9 +7873,8 @@ Example::
     >>> weights = torch.tensor([0, 10, 3, 0], dtype=torch.float) # create a tensor of weights
     >>> torch.multinomial(weights, 2)
     tensor([1, 2])
-    >>> torch.multinomial(weights, 4) # ERROR!
-    RuntimeError: invalid argument 2: invalid multinomial distribution (with replacement=False,
-    not enough non-negative category to sample) at ../aten/src/TH/generic/THTensorRandom.cpp:320
+    >>> torch.multinomial(weights, 5) # ERROR!
+    RuntimeError: cannot sample n_sample > prob_dist.size(-1) samples without replacement
     >>> torch.multinomial(weights, 4, replacement=True)
     tensor([ 2,  1,  1,  1])
 """.format(