Reformat architecture overview and embed Litho Lesson video
Reformat architecture overview and embed Litho Lesson video

Differential Revision: D19292409

fbshipit-source-id: 671f3a0f4f0138bb384ffc2281a8d225481656cc

facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho