Fixes formatting of vander, count_nonzero, DistributedSampler documentation (#41025)
Summary:
Bundle of small edits to fix formatting.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/41025
Differential Revision: D22398364
Pulled By: mruberry
fbshipit-source-id: 8d484cb52a1cf4a8eb1f64914574250c9fd5043d
