Documentation for cdist (#25221)
Summary:
https://github.com/pytorch/pytorch/issues/21730
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25221
Differential Revision: D17073908
Pulled By: ifedan
fbshipit-source-id: 19e2534183d6a2a7e9cdfcee4734cff1b124e05a
