Update CHANGELOG.md
Update CHANGELOG.md

* Add entry to table of contents.
* Add reminder to Swift 5.1 section.
* Indent single-parameter example code.
sschiau/swift,devincoughlin/swift,stephentyrone/swift,jmgc/swift,rudkx/swift,karwa/swift,ahoppen/swift,hooman/swift,atrick/swift,aschwaighofer/swift,karwa/swift,karwa/swift,rudkx/swift,parkera/swift,glessard/swift,gribozavr/swift,gribozavr/swift,JGiola/swift,allevato/swift,xwu/swift,glessard/swift,benlangmuir/swift,CodaFi/swift,benlangmuir/swift,benlangmuir/swift,lorentey/swift,shahmishal/swift,gregomni/swift,shajrawi/swift,glessard/swift,atrick/swift,stephentyrone/swift,nathawes/swift,airspeedswift/swift,roambotics/swift,gribozavr/swift,hooman/swift,harlanhaskins/swift,jmgc/swift,atrick/swift,ahoppen/swift,atrick/swift,airspeedswift/swift,lorentey/swift,parkera/swift,devincoughlin/swift,devincoughlin/swift,parkera/swift,xwu/swift,gregomni/swift,shahmishal/swift,gregomni/swift,JGiola/swift,CodaFi/swift,CodaFi/swift,gregomni/swift,shajrawi/swift,nathawes/swift,tkremenek/swift,xedin/swift,gribozavr/swift,shajrawi/swift,airspeedswift/swift,aschwaighofer/swift,karwa/swift,JGiola/swift,JGiola/swift,rudkx/swift,jmgc/swift,lorentey/swift,roambotics/swift,jckarter/swift,xedin/swift,gribozavr/swift,xwu/swift,ahoppen/swift,ahoppen/swift,airspeedswift/swift,jckarter/swift,nathawes/swift,tkremenek/swift,rudkx/swift,karwa/swift,parkera/swift,jckarter/swift,shahmishal/swift,stephentyrone/swift,hooman/swift,allevato/swift,airspeedswift/swift,sschiau/swift,harlanhaskins/swift,jmgc/swift,xwu/swift,jmgc/swift,shajrawi/swift,benlangmuir/swift,sschiau/swift,xwu/swift,tkremenek/swift,roambotics/swift,shajrawi/swift,tkremenek/swift,tkremenek/swift,atrick/swift,gregomni/swift,atrick/swift,aschwaighofer/swift,harlanhaskins/swift,jmgc/swift,xedin/swift,apple/swift,nathawes/swift,nathawes/swift,shahmishal/swift,gregomni/swift,sschiau/swift,allevato/swift,glessard/swift,xedin/swift,stephentyrone/swift,rudkx/swift,harlanhaskins/swift,parkera/swift,sschiau/swift,shahmishal/swift,shahmishal/swift,karwa/swift,karwa/swift,harlanhaskins/swift,karwa/swift,allevato/swift,lorentey/swift,shahmishal/swift,rudkx/swift,apple/swift,apple/swift,hooman/swift,lorentey/swift,shajrawi/swift,shahmishal/swift,CodaFi/swift,devincoughlin/swift,roambotics/swift,CodaFi/swift,xedin/swift,apple/swift,xedin/swift,apple/swift,devincoughlin/swift,jmgc/swift,gribozavr/swift,aschwaighofer/swift,hooman/swift,sschiau/swift,jckarter/swift,parkera/swift,CodaFi/swift,airspeedswift/swift,CodaFi/swift,roambotics/swift,benlangmuir/swift,jckarter/swift,tkremenek/swift,xedin/swift,jckarter/swift,gribozavr/swift,harlanhaskins/swift,glessard/swift,allevato/swift,devincoughlin/swift,hooman/swift,xwu/swift,parkera/swift,harlanhaskins/swift,stephentyrone/swift,aschwaighofer/swift,nathawes/swift,lorentey/swift,aschwaighofer/swift,devincoughlin/swift,sschiau/swift,stephentyrone/swift,aschwaighofer/swift,allevato/swift,JGiola/swift,lorentey/swift,roambotics/swift,stephentyrone/swift,hooman/swift,xwu/swift,apple/swift,jckarter/swift,allevato/swift,benlangmuir/swift,gribozavr/swift,lorentey/swift,parkera/swift,tkremenek/swift,ahoppen/swift,nathawes/swift,devincoughlin/swift,JGiola/swift,glessard/swift,sschiau/swift,xedin/swift,shajrawi/swift,airspeedswift/swift,ahoppen/swift,shajrawi/swift