small fix for documentation typos in fatal/reflection.h
small fix for documentation typos in fatal/reflection.h

Summary:
As titled.

Also a place may be out-dated. See in-line comment.

Reviewed By: juchem

Differential Revision: D3559550

fbshipit-source-id: 37493eff5e6544988278528002fa017d379f40fb

LinusU/fbthrift,getyourguide/fbthrift,SergeyMakarenko/fbthrift,LinusU/fbthrift,LinusU/fbthrift,SergeyMakarenko/fbthrift,facebook/fbthrift,LinusU/fbthrift,SergeyMakarenko/fbthrift,facebook/fbthrift,SergeyMakarenko/fbthrift,SergeyMakarenko/fbthrift,getyourguide/fbthrift,LinusU/fbthrift,facebook/fbthrift,getyourguide/fbthrift,getyourguide/fbthrift,SergeyMakarenko/fbthrift,facebook/fbthrift,facebook/fbthrift,SergeyMakarenko/fbthrift,SergeyMakarenko/fbthrift,SergeyMakarenko/fbthrift,getyourguide/fbthrift,getyourguide/fbthrift,SergeyMakarenko/fbthrift,getyourguide/fbthrift,SergeyMakarenko/fbthrift,LinusU/fbthrift,getyourguide/fbthrift,SergeyMakarenko/fbthrift,facebook/fbthrift,getyourguide/fbthrift,LinusU/fbthrift,LinusU/fbthrift,LinusU/fbthrift,facebook/fbthrift,getyourguide/fbthrift,facebook/fbthrift,LinusU/fbthrift,getyourguide/fbthrift,LinusU/fbthrift,facebook/fbthrift,getyourguide/fbthrift