Elaborate on codepoints and the :binary module in String.to_char_list

Author: alco

lib/elixir/lib/string.ex

@@ -1381,6 +1381,13 @@ defmodule String do
  @doc """
  Converts a string into a char list.
 
+ Specifically, this functions takes a UTF-8 encoded binary and returns a list of its integer
+ codepoints. It is similar to `codepoints/1` except that the latter returns a list of codepoints as
+ strings.
+
+ In case you need to work with bytes, take a look at the
+ [`:binary` module](http://erlang.org/doc/man/binary.html).
+
  ## Examples
 
  iex> String.to_char_list("æß")