Update CHANGELOG.md (Swift 5.0 => Swift 4.2) (#14925)
Update CHANGELOG.md (Swift 5.0 => Swift 4.2) (#14925)

<https://swift.org/blog/4-2-release-process/>
devincoughlin/swift,practicalswift/swift,jopamer/swift,CodaFi/swift,sschiau/swift,harlanhaskins/swift,atrick/swift,gregomni/swift,allevato/swift,airspeedswift/swift,shahmishal/swift,brentdax/swift,jckarter/swift,rudkx/swift,hooman/swift,brentdax/swift,hooman/swift,karwa/swift,practicalswift/swift,airspeedswift/swift,harlanhaskins/swift,brentdax/swift,austinzheng/swift,aschwaighofer/swift,lorentey/swift,CodaFi/swift,jckarter/swift,jmgc/swift,lorentey/swift,brentdax/swift,harlanhaskins/swift,devincoughlin/swift,xwu/swift,xwu/swift,glessard/swift,glessard/swift,harlanhaskins/swift,huonw/swift,jopamer/swift,huonw/swift,tkremenek/swift,parkera/swift,hooman/swift,karwa/swift,amraboelela/swift,danielmartin/swift,shahmishal/swift,gribozavr/swift,austinzheng/swift,ahoppen/swift,roambotics/swift,hooman/swift,ahoppen/swift,ahoppen/swift,gribozavr/swift,gribozavr/swift,danielmartin/swift,jckarter/swift,hooman/swift,jmgc/swift,apple/swift,tjw/swift,stephentyrone/swift,xwu/swift,amraboelela/swift,jopamer/swift,shajrawi/swift,CodaFi/swift,aschwaighofer/swift,jmgc/swift,roambotics/swift,devincoughlin/swift,natecook1000/swift,atrick/swift,CodaFi/swift,shahmishal/swift,devincoughlin/swift,brentdax/swift,stephentyrone/swift,gribozavr/swift,JGiola/swift,allevato/swift,stephentyrone/swift,CodaFi/swift,nathawes/swift,rudkx/swift,roambotics/swift,aschwaighofer/swift,gribozavr/swift,aschwaighofer/swift,karwa/swift,karwa/swift,parkera/swift,practicalswift/swift,natecook1000/swift,JGiola/swift,rudkx/swift,allevato/swift,xwu/swift,shajrawi/swift,CodaFi/swift,sschiau/swift,apple/swift,atrick/swift,nathawes/swift,gregomni/swift,nathawes/swift,aschwaighofer/swift,apple/swift,JGiola/swift,xwu/swift,apple/swift,roambotics/swift,airspeedswift/swift,lorentey/swift,huonw/swift,lorentey/swift,natecook1000/swift,tkremenek/swift,gregomni/swift,jopamer/swift,rudkx/swift,airspeedswift/swift,devincoughlin/swift,xedin/swift,tjw/swift,danielmartin/swift,xedin/swift,lorentey/swift,JGiola/swift,benlangmuir/swift,brentdax/swift,practicalswift/swift,hooman/swift,karwa/swift,danielmartin/swift,glessard/swift,shahmishal/swift,gregomni/swift,allevato/swift,austinzheng/swift,gregomni/swift,aschwaighofer/swift,huonw/swift,ahoppen/swift,austinzheng/swift,allevato/swift,ahoppen/swift,alblue/swift,stephentyrone/swift,ahoppen/swift,JGiola/swift,benlangmuir/swift,stephentyrone/swift,austinzheng/swift,gribozavr/swift,gregomni/swift,nathawes/swift,benlangmuir/swift,allevato/swift,airspeedswift/swift,danielmartin/swift,tkremenek/swift,lorentey/swift,danielmartin/swift,tjw/swift,harlanhaskins/swift,harlanhaskins/swift,devincoughlin/swift,sschiau/swift,huonw/swift,brentdax/swift,tjw/swift,roambotics/swift,austinzheng/swift,sschiau/swift,benlangmuir/swift,jmgc/swift,practicalswift/swift,apple/swift,shajrawi/swift,jckarter/swift,karwa/swift,xedin/swift,sschiau/swift,lorentey/swift,hooman/swift,CodaFi/swift,tkremenek/swift,jmgc/swift,benlangmuir/swift,karwa/swift,nathawes/swift,atrick/swift,huonw/swift,xwu/swift,alblue/swift,devincoughlin/swift,amraboelela/swift,allevato/swift,rudkx/swift,parkera/swift,practicalswift/swift,shahmishal/swift,shajrawi/swift,sschiau/swift,xedin/swift,amraboelela/swift,nathawes/swift,jopamer/swift,jmgc/swift,glessard/swift,parkera/swift,shajrawi/swift,glessard/swift,shahmishal/swift,parkera/swift,jckarter/swift,rudkx/swift,airspeedswift/swift,stephentyrone/swift,jckarter/swift,atrick/swift,shahmishal/swift,JGiola/swift,airspeedswift/swift,huonw/swift,alblue/swift,xedin/swift,alblue/swift,alblue/swift,nathawes/swift,xedin/swift,shahmishal/swift,austinzheng/swift,sschiau/swift,alblue/swift,gribozavr/swift,roambotics/swift,tjw/swift,sschiau/swift,natecook1000/swift,shajrawi/swift,atrick/swift,stephentyrone/swift,natecook1000/swift,xedin/swift,amraboelela/swift,xedin/swift,glessard/swift,devincoughlin/swift,apple/swift,shajrawi/swift,tkremenek/swift,tjw/swift,jopamer/swift,tkremenek/swift,jckarter/swift,natecook1000/swift,tjw/swift,tkremenek/swift,benlangmuir/swift,parkera/swift,parkera/swift,aschwaighofer/swift,practicalswift/swift,practicalswift/swift,jmgc/swift,lorentey/swift,danielmartin/swift,harlanhaskins/swift,amraboelela/swift,natecook1000/swift,gribozavr/swift,shajrawi/swift,alblue/swift,amraboelela/swift,karwa/swift,xwu/swift,jopamer/swift,parkera/swift