Update README.md (#130)
Update README.md (#130)

Summary:
typo fix
Pull Request resolved: https://github.com/facebookincubator/mvfst/pull/130

Reviewed By: yangchi

Differential Revision: D21549794

Pulled By: lnicco

fbshipit-source-id: 0c1fbb40a4cf7ddf78d2051910453cc249f66090

facebookincubator/mvfst,facebookincubator/mvfst,facebookincubator/mvfst,facebookincubator/mvfst,facebookincubator/mvfst