Fixed Softmax doc to specify dimension to prevent warning in 1.1.0. (#20310)
Summary:
See Issue #20301
Specifying dim in docstring example to prevent UserWarning.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20310
Differential Revision: D15277734
Pulled By: ezyang
fbshipit-source-id: 2e8b748dbe743675a5a538ccbe97713aad02e8ac
