[sparsity][doc] Docstring for WeightNormSparsifier (#65294)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65294
This adds the docstring documentation to the WeightNormSparsifier and adds the typehints for the constructor args.
Note, this does not require testing as only the doc is changed.
Test Plan: Imported from OSS
Reviewed By: gchanan
Differential Revision: D31186827
Pulled By: z-a-f
fbshipit-source-id: c5010c9bba25b074c4cc6c88f251474b758f950d
