[ONNX] Add supplementary tests and description for custom_opsets param from torch.onnx.export() function. (#62085) (#64372)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64372
custom_opsets arg from torch.onnx.export() is no needed to be removed.
Add some supplementary description and tests for easier understanding.
Test Plan: Imported from OSS
Reviewed By: ezyang
Differential Revision: D30905269
Pulled By: malfet
fbshipit-source-id: 489fbee0e2c1d6c5405c9bf7dfd85223ed981a44
Co-authored-by: hwangdeyu <dejack953@outlook.com>
