[4/n] Remove references to TorchScript in PyTorch docs (pytorch#158317)

Summary: jit.rst

Test Plan:
CI

Rollback Plan:

Differential Revision: D78309840

Pull Request resolved: pytorch#158317
Approved by: https://github.com/svekars, https://github.com/zhxchen17

Author: yiming0416