Change docs to use recursive script API (#21612)
Summary:
Use the recursive script API in the existing docs
TODO:
* Migration guide for 1.1 -> 1.2
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21612
Pulled By: driazati
Differential Revision: D16553734
fbshipit-source-id: fb6be81a950224390bd5d19b9b3de2d97b3dc515
