Add link to tutorial in Timer doc (#50374)
Summary:
Because I have a hard time finding this tutorial every time I need it. So I'm sure other people have the same issue :D
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50374
Reviewed By: zhangguanheng66
Differential Revision: D25872173
Pulled By: albanD
fbshipit-source-id: f34f719606e58487baf03c73dcbd255017601a09
