Create README.md with documentation and usage (#4457)
Create README.md with documentation and usage (#4457)

Per https://github.com/prettier/prettier/pull/2772#discussion_r137921858
facebook/jest,cpojer/jest,ide/jest,facebook/jest,bookman25/jest,ide/jest,cpojer/jest,bookman25/jest,ide/jest,bookman25/jest,facebook/jest,cpojer/jest