Replace use of "item(s)" with "element(s)" in List module (#8633)
Replace use of "item(s)" with "element(s)" in List module (#8633)

The usage of items and elements was mixed,
but Erlang refers to them as Elements,
and Enumerable also refer to them as elements,
so I took the liberty to standardize its usage.
pedrosnk/elixir,lexmag/elixir,kelvinst/elixir,pedrosnk/elixir,kelvinst/elixir,joshprice/elixir,ggcampinho/elixir,ggcampinho/elixir,kimshrier/elixir,kimshrier/elixir,michalmuskala/elixir,elixir-lang/elixir,lexmag/elixir