Updates serialization note to explain versioned symbols and dynamic versioning (#41395)
Summary:
Doc update intended to clarify and expand our current serialization behavior, including explaining the difference between torch.save/torch.load, torch.nn.Module.state_dict/torch.nn.Module.load_state_dict, and torch.jit.save/torch.jit.load. Also explains, for the time, when historic serialized Torchscript behavior is preserved and our recommendation for preserving behavior (using the same PyTorch version to consume a model as produced it).
Pull Request resolved: https://github.com/pytorch/pytorch/pull/41395
Reviewed By: ngimel
Differential Revision: D22560538
Pulled By: mruberry
fbshipit-source-id: dbc2f1bb92ab61ff2eca4888febc21f7dda76ba1
