Fix a typo in ${NEW} variable in Post-processing tools for diagnostics section
Fix a typo in ${NEW} variable in Post-processing tools for diagnostics section

While reading up I realized there is a typo in: `how to use  utils/process-stats-dir.py`. The example asks to use OLD and NEW compiler but the documentation uses only ${OLD} compiler in example
parkera/swift,ahoppen/swift,aschwaighofer/swift,hooman/swift,aschwaighofer/swift,xwu/swift,allevato/swift,stephentyrone/swift,tkremenek/swift,jmgc/swift,parkera/swift,CodaFi/swift,airspeedswift/swift,jmgc/swift,airspeedswift/swift,lorentey/swift,nathawes/swift,karwa/swift,xwu/swift,roambotics/swift,glessard/swift,jckarter/swift,lorentey/swift,harlanhaskins/swift,CodaFi/swift,apple/swift,karwa/swift,karwa/swift,jckarter/swift,atrick/swift,ahoppen/swift,lorentey/swift,karwa/swift,harlanhaskins/swift,aschwaighofer/swift,lorentey/swift,aschwaighofer/swift,gregomni/swift,airspeedswift/swift,rudkx/swift,benlangmuir/swift,ahoppen/swift,roambotics/swift,harlanhaskins/swift,hooman/swift,atrick/swift,rudkx/swift,jckarter/swift,apple/swift,apple/swift,benlangmuir/swift,stephentyrone/swift,glessard/swift,CodaFi/swift,karwa/swift,allevato/swift,aschwaighofer/swift,tkremenek/swift,hooman/swift,lorentey/swift,harlanhaskins/swift,apple/swift,nathawes/swift,allevato/swift,nathawes/swift,karwa/swift,nathawes/swift,rudkx/swift,gregomni/swift,JGiola/swift,hooman/swift,roambotics/swift,rudkx/swift,lorentey/swift,tkremenek/swift,CodaFi/swift,aschwaighofer/swift,parkera/swift,benlangmuir/swift,aschwaighofer/swift,gribozavr/swift,rudkx/swift,harlanhaskins/swift,airspeedswift/swift,allevato/swift,hooman/swift,atrick/swift,jmgc/swift,gribozavr/swift,benlangmuir/swift,gribozavr/swift,roambotics/swift,jckarter/swift,nathawes/swift,xwu/swift,gregomni/swift,airspeedswift/swift,jckarter/swift,xwu/swift,lorentey/swift,airspeedswift/swift,gregomni/swift,karwa/swift,tkremenek/swift,CodaFi/swift,parkera/swift,stephentyrone/swift,jmgc/swift,allevato/swift,gribozavr/swift,xwu/swift,gregomni/swift,harlanhaskins/swift,tkremenek/swift,CodaFi/swift,nathawes/swift,jmgc/swift,apple/swift,JGiola/swift,stephentyrone/swift,apple/swift,roambotics/swift,allevato/swift,parkera/swift,lorentey/swift,tkremenek/swift,parkera/swift,atrick/swift,stephentyrone/swift,jckarter/swift,stephentyrone/swift,hooman/swift,tkremenek/swift,xwu/swift,JGiola/swift,atrick/swift,glessard/swift,CodaFi/swift,JGiola/swift,hooman/swift,JGiola/swift,karwa/swift,gribozavr/swift,atrick/swift,glessard/swift,glessard/swift,gribozavr/swift,ahoppen/swift,gribozavr/swift,rudkx/swift,nathawes/swift,jmgc/swift,airspeedswift/swift,allevato/swift,harlanhaskins/swift,glessard/swift,benlangmuir/swift,gregomni/swift,stephentyrone/swift,parkera/swift,xwu/swift,roambotics/swift,JGiola/swift,ahoppen/swift,jckarter/swift,gribozavr/swift,parkera/swift,benlangmuir/swift,ahoppen/swift,jmgc/swift