[README] Update the Xcode version.
[README] Update the Xcode version.

tkremenek/swift,parkera/swift,roambotics/swift,roambotics/swift,jckarter/swift,apple/swift,rudkx/swift,allevato/swift,nathawes/swift,hooman/swift,parkera/swift,CodaFi/swift,hooman/swift,airspeedswift/swift,gregomni/swift,allevato/swift,xwu/swift,allevato/swift,allevato/swift,atrick/swift,atrick/swift,tkremenek/swift,stephentyrone/swift,roambotics/swift,nathawes/swift,jckarter/swift,apple/swift,hooman/swift,glessard/swift,parkera/swift,stephentyrone/swift,parkera/swift,stephentyrone/swift,JGiola/swift,jmgc/swift,stephentyrone/swift,benlangmuir/swift,xwu/swift,nathawes/swift,airspeedswift/swift,CodaFi/swift,airspeedswift/swift,stephentyrone/swift,jmgc/swift,atrick/swift,parkera/swift,roambotics/swift,tkremenek/swift,tkremenek/swift,xwu/swift,ahoppen/swift,atrick/swift,atrick/swift,benlangmuir/swift,jckarter/swift,parkera/swift,glessard/swift,JGiola/swift,jmgc/swift,hooman/swift,allevato/swift,jmgc/swift,gregomni/swift,rudkx/swift,airspeedswift/swift,hooman/swift,glessard/swift,JGiola/swift,ahoppen/swift,gregomni/swift,benlangmuir/swift,nathawes/swift,roambotics/swift,jckarter/swift,jmgc/swift,jmgc/swift,CodaFi/swift,ahoppen/swift,jckarter/swift,tkremenek/swift,xwu/swift,JGiola/swift,apple/swift,allevato/swift,JGiola/swift,glessard/swift,rudkx/swift,rudkx/swift,tkremenek/swift,apple/swift,roambotics/swift,nathawes/swift,ahoppen/swift,parkera/swift,jmgc/swift,xwu/swift,airspeedswift/swift,jckarter/swift,airspeedswift/swift,benlangmuir/swift,parkera/swift,stephentyrone/swift,CodaFi/swift,nathawes/swift,benlangmuir/swift,benlangmuir/swift,gregomni/swift,apple/swift,rudkx/swift,allevato/swift,atrick/swift,ahoppen/swift,tkremenek/swift,ahoppen/swift,rudkx/swift,stephentyrone/swift,JGiola/swift,CodaFi/swift,gregomni/swift,glessard/swift,gregomni/swift,xwu/swift,hooman/swift,glessard/swift,CodaFi/swift,xwu/swift,airspeedswift/swift,hooman/swift,apple/swift,nathawes/swift,jckarter/swift,CodaFi/swift