[nfc] Fixed typos in comments in Sort.swift
[nfc] Fixed typos in comments in Sort.swift

There is still an incongruity between where `srcHigh` and `destHigh` are displayed in the diagram:

`srcHigh` is shown at the location it logically represents, not its true position which is one past that, whereas `destHigh` (as well as `bufferHigh`) is shown at its true position (past the end) not at the location it logically represents.

I am not sure if that is intentional.
JGiola/swift,hooman/swift,xwu/swift,glessard/swift,roambotics/swift,rudkx/swift,gregomni/swift,parkera/swift,JGiola/swift,benlangmuir/swift,parkera/swift,xwu/swift,benlangmuir/swift,JGiola/swift,apple/swift,tkremenek/swift,roambotics/swift,atrick/swift,hooman/swift,atrick/swift,benlangmuir/swift,glessard/swift,gregomni/swift,tkremenek/swift,tkremenek/swift,xwu/swift,atrick/swift,rudkx/swift,parkera/swift,hooman/swift,xwu/swift,hooman/swift,tkremenek/swift,JGiola/swift,parkera/swift,gregomni/swift,JGiola/swift,parkera/swift,ahoppen/swift,ahoppen/swift,ahoppen/swift,xwu/swift,parkera/swift,glessard/swift,hooman/swift,gregomni/swift,benlangmuir/swift,xwu/swift,gregomni/swift,apple/swift,apple/swift,roambotics/swift,parkera/swift,benlangmuir/swift,tkremenek/swift,ahoppen/swift,roambotics/swift,roambotics/swift,hooman/swift,parkera/swift,ahoppen/swift,rudkx/swift,JGiola/swift,atrick/swift,hooman/swift,roambotics/swift,apple/swift,atrick/swift,glessard/swift,ahoppen/swift,rudkx/swift,xwu/swift,tkremenek/swift,rudkx/swift,glessard/swift,benlangmuir/swift,glessard/swift,tkremenek/swift,apple/swift,rudkx/swift,atrick/swift,apple/swift,gregomni/swift