Update tutorial.md
Update tutorial.md

Summary:
handlers
Closes https://github.com/facebook/wangle/pull/43

Differential Revision: D3223484

Pulled By: elliottneilclark

fb-gh-sync-id: 47599ff26a55e5bf293f6e3660129713044d9102
fbshipit-source-id: 47599ff26a55e5bf293f6e3660129713044d9102

facebook/wangle,Dalzhim/wangle,facebook/wangle,Dalzhim/wangle,facebook/wangle