pytorch

1039b95f - [autograd] add documentation about multithread autograd (#37020)

[autograd] add documentation about multithread autograd (#37020) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/37020 Add multithread autograd documentation to the doc note. Test Plan: Imported from OSS Differential Revision: D21260996 Pulled By: wanchaol fbshipit-source-id: 91d523560268ae62d4c6d773121b282ba837a561