Fix broken javadoc URL in README (#54434)
Summary:
The link in the README was broken
Pull Request resolved: https://github.com/pytorch/pytorch/pull/54434
Reviewed By: ailzhang
Differential Revision: D27328733
Pulled By: nairbv
fbshipit-source-id: 12ebb6f66983f9348a90b9738fbd9f3f2660c2d1
