Doc update for R.file.*
Doc update for R.file.*

tomasharkema/R.swift,ntnmrndn/R.swift,mac-cain13/R.swift,mac-cain13/R.swift,renrawnalon/R.swift,mac-cain13/R.swift,renrawnalon/R.swift,ntnmrndn/R.swift,tomasharkema/R.swift