Document first line behavior in update message
Document first line behavior in update message

Test Plan: (This diff)

Reviewers: epriestley, jungejason

Reviewed By: jungejason

CC: aran, Koolvin

Differential Revision: https://secure.phabricator.com/D2389

haskell-infra/arcanist,phacility/arcanist,eSpark/arcanist,haskell-infra/arcanist,wharris/arcanist,coursera/arcanist,jra3/arcanist,dguo-coursera/arcanist,eSpark/arcanist,wharris/arcanist,alexmv/arcanist,haskell-infra/arcanist,calblueprint/arcanist,r4nt/arcanist,r4nt/arcanist,wxstars/arcanist,chundongwang/arcanist,sneakpeeq/arcanist,calblueprint/arcanist,aik099/arcanist,uber/arcanist,kevinseelbach/arcanist,wharris/arcanist,wikimedia/phabricator-arcanist,coursera/arcanist,memsql/arcanist,phacility/arcanist,PageUpPeopleOrg/arcanist-patches,folsom-labs/arcanist,aik099/arcanist,jra3/arcanist,codelabs-ch/arcanist,fivestars/arcanist,uber/arcanist,uber/arcanist,fivestars/arcanist,dguo-coursera/arcanist,hach-que/arcanist,wxstars/arcanist,PageUpPeopleOrg/arcanist-patches,folsom-labs/arcanist,Symplicity/arcanist,calblueprint/arcanist,KieranHayes/arcanist,zhihu/arcanist,r4nt/arcanist,eSpark/arcanist,chundongwang/arcanist,Khan/arcanist,r4nt/arcanist,coursera/arcanist,julkiewicz/arcanist,PageUpPeopleOrg/arcanist-patches,Symplicity/arcanist,Khan/arcanist,dguo-coursera/arcanist,folsom-labs/arcanist,wharris/arcanist,julkiewicz/arcanist,dguo-coursera/arcanist,julkiewicz/arcanist,zhihu/arcanist,haskell-infra/arcanist,wikimedia/phabricator-arcanist,hach-que/arcanist,jra3/arcanist,KieranHayes/arcanist,wikimedia/phabricator-arcanist,sneakpeeq/arcanist,kevinseelbach/arcanist,codelabs-ch/arcanist,uber/arcanist,chundongwang/arcanist,aik099/arcanist,memsql/arcanist,coursera/arcanist,alexmv/arcanist,wxstars/arcanist,fivestars/arcanist,kevinseelbach/arcanist,phacility/arcanist,kevinseelbach/arcanist,eSpark/arcanist,alexmv/arcanist,codelabs-ch/arcanist,PageUpPeopleOrg/arcanist-patches,jra3/arcanist,memsql/arcanist,folsom-labs/arcanist,phacility/arcanist,codelabs-ch/arcanist,zhihu/arcanist,fivestars/arcanist,hach-que/arcanist,sneakpeeq/arcanist,zhihu/arcanist,sneakpeeq/arcanist,hach-que/arcanist,alexmv/arcanist,KieranHayes/arcanist,phacility/arcanist,Symplicity/arcanist,Khan/arcanist,wikimedia/phabricator-arcanist,Symplicity/arcanist,KieranHayes/arcanist,codelabs-ch/arcanist,calblueprint/arcanist,Khan/arcanist,wxstars/arcanist,aik099/arcanist,julkiewicz/arcanist,memsql/arcanist,chundongwang/arcanist