Use at::zeros instead of torch::zeros in non-differentiable example (#15527)
Summary:
There was a typo in C++ docs.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15527
Differential Revision: D13547858
Pulled By: soumith
fbshipit-source-id: 1f5250206ca6e13b1b1443869b1e1c837a756cb5
