torch.package change `Folder` to `Directory` and add doc strings (#56925)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/56925
Test Plan: Imported from OSS
Reviewed By: suo
Differential Revision: D28002145
Pulled By: Lilyjjo
fbshipit-source-id: 6265970202d1530c4fb7ea10011b0e09094037d5
