Add copy button to code snippets in docs (#63149)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/63149
Test Plan: Imported from OSS
Reviewed By: navahgar, albanD
Differential Revision: D30308891
Pulled By: anjali411
fbshipit-source-id: ad51180ab2f27c4525682b2603bbf753bb8f1ce9
