Updated code example in README
Updated code example in README

creativepragmatics/AFOAuth2Manager,AFNetworking/AFOAuth2Manager,Mombo-Labs/AFOAuth2Manager,ServiceNow/AFOAuth2Manager,isaacroldan/AFOAuth2Manager,lowell/AFOAuth2Manager,brigade/AFOAuth2Client,triage/AFOAuth2Manager,OmarPedraza/AFOAuth2Manager,jaredsinclair/AFOAuth2Manager,zyncro/AFOAuth2Manager,chairish/AFOAuth2Manager