Corrected a wrong namespace comment
Corrected a wrong namespace comment

Summary: Pull Request resolved: https://github.com/facebook/folly/pull/912

Reviewed By: Orvid

Differential Revision: D9344568

Pulled By: yfeldblum

fbshipit-source-id: bcafaab895454f21c3005825003916d771210d33

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly