Move TorchScript language reference to its own page (#31138)
Summary:
Stacked PRs
* #31146 - [jit] Cleanup after moving language reference
* **#31138 - [jit] Move TorchScript language reference to its own page**
Preview: https://driazati.github.io/pytorch_doc_previews/jit.html#torchscript-language
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31138
Pulled By: driazati
Differential Revision: D19167375
fbshipit-source-id: d37110d85fc8b8d2c741be49846e873de1357c2a
