Fix link to py-spy content in contribution guide TOC (#31760)
Summary:
The extra dashes are breaking the link here
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31760
Differential Revision: D19697301
Pulled By: ezyang
fbshipit-source-id: 65de026b9016dc8689c9dac9efb8aafd00b535cd
