add instructions for NVIDIA Jetson platforms (#18990)
Summary:
Thanks to dusty-nv , we now have Stable and Weekly wheels provided for the NVIDIA Jetson Platform. They require JetPack 4.2.
He's also maintaining source build instructions.
This PR adds links to the binaries and source build instructions to the README.
The links are dynamic, so when new stable / weekly wheels are available, Dustin will update the same URL to point to the new files
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18990
Differential Revision: D14820158
Pulled By: soumith
fbshipit-source-id: 761a56557decb72ad9c1b9f8a2745667f558eec3
