Edits to ReadMe file (#27808)
Summary:
Grammar edits to the Readme file to make it read better in English
Pull Request resolved: https://github.com/pytorch/pytorch/pull/27808
Differential Revision: D17901414
Pulled By: soumith
fbshipit-source-id: 02e67289dafaf9280cb1c3bb2f37087cd134cc23
