Correct typo in README
Correct typo in README

The sample `.laptop.local` incorrectly referred to
`gem_install_or_upgrade` instead of `gem_install_or_update`.

nipe0324/laptop,nickisnoble/laptop,qq3561501/laptop,Nunnery/laptop,anongtech/laptop,robodisco/laptop,irfanah/laptop,darrellpratt/laptop,camerondunford/laptop,inthebestway/laptop,jakt/laptop,Vermonster/laptop,tomtoday/laptop,estoeckli/laptop,nathansmyth/laptop,schireson/laptop,jszod/laptop,obitum/laptop,vorleakchy/laptop,MAubreyK/laptop,dholdren/laptop,ririjin/laptop,UseFedora/laptop,sphillips/laptop,rebaselabs/laptop,gobble/laptop,xuebinglee/laptop,CapeSepias/laptop,thoughtbot/laptop,mcritchlow/laptop,akhosravian/laptop,nikeshashar/laptop,clef/laptop,P15/laptop,paigetech/laptop,jay3126/laptop,omc/laptop,SPBTV/laptop,massimoksi/laptop,Kajabi/laptop,freistil/laptop,dleve123/laptop,hacktiv8/macmini,Hatlen/laptop,benliscio/laptop,jopecko/laptop,lrmunoz/laptop,cabouffard/laptop,Recombine/laptop,netguru/laptop,fievelk/laptop,GivewellGetwell/laptop,bhendo/laptop,vulk/laptop,akhosravian/laptop,estoeckli/laptop,avvo/laptop,RyanMacG/laptop,griffio/laptop,kickstarter/laptop,dfang/laptop,linkyndy/laptop,DRAKUN/laptop,policygenius/laptop,archaelus/laptop,BCoulange/laptop,pygeek/laptop,ffleming/laptop,jacobsimeon/laptop,frankcash/laptop,peterberkenbosch/laptop,jjwon0/laptop,zBMNForks/laptop,Flightlogger/laptop,webdev1001/laptop,EpionHealth/laptop,policygenius/laptop,SpecializedBicycles/laptop,iphilgood/laptop,OKAMca/laptop,steshaw/laptop,burningpony/laptop,eroluysal/laptop,Jyaasa/laptop,notrab/laptop,hannesfostie/laptop,jaischeema/laptop,kapziel/laptop,paulghaddad/laptop,omahacodeschool/laptop,tonyd256/laptop,patrickmelvin/laptop,jjwon/laptop,karthick03/laptop,agbodike/laptop,jaisonerick/laptop