Add remaining ToCs to ToC lint (#56487)
Summary:
The lint was originally added in https://github.com/pytorch/pytorch/issues/54974, but at the time I didn't realize that these other Markdown files also each have a table of contents:
- `GLOSSARY.md`
- `torch/csrc/jit/OVERVIEW.md`
- `torch/csrc/jit/docs/serialization.md`
- `torch/fx/OVERVIEW.md`
This PR adds those files to the lint, and also changes the rule from using a fixed list of filenames to a `git grep` command that finds all Markdown files containing this magic comment:
```md
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56487
Test Plan: The "Lint / toc" job in GitHub Actions.
Reviewed By: janeyx99
Differential Revision: D27884885
Pulled By: samestep
fbshipit-source-id: 5462437502b17fba93abf5098e21754bf566a4fe
