Add note about in-place weight modification for nn.Embedding (#45595)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/26596
Pull Request resolved: https://github.com/pytorch/pytorch/pull/45595
Reviewed By: albanD
Differential Revision: D24143456
Pulled By: mruberry
fbshipit-source-id: a884a32809105ce16959b40ec745ec873b3c8375
