Minor cosmetic improvement for LatencyInjectionRoute
Minor cosmetic improvement for LatencyInjectionRoute

Summary: * add comments for the request level latency parameters

Reviewed By: stuclar

Differential Revision: D34634247

fbshipit-source-id: 6d8d1745dddfbe5b5a532bbee7613b4b4bfdc7bb

facebook/mcrouter,facebook/mcrouter,facebook/mcrouter,facebook/mcrouter