Fix typo to add clarity (#1525)
Summary:
Nit but it should add clarity to the doc.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1525
Reviewed By: aaronenyeshi
Differential Revision: D44681135
Pulled By: xuzhao9
fbshipit-source-id: c4b0c3bf303df8fab12b128fe492fb8f8809d63d
