Update String.replace/4 and String.split/3 docs (#9876)
Update String.replace/4 and String.split/3 docs (#9876)


kelvinst/elixir,kelvinst/elixir,pedrosnk/elixir,joshprice/elixir,pedrosnk/elixir,kimshrier/elixir,kimshrier/elixir,michalmuskala/elixir,ggcampinho/elixir,elixir-lang/elixir,ggcampinho/elixir