Fix typespecs and code comments

Author: josevalim

lib/elixir/lib/kernel/parallel_compiler.ex

@@ -155,7 +155,8 @@ defmodule Kernel.ParallelCompiler do
   """
   @doc since: "1.6.0"
   @spec require([Path.t()], keyword()) ::
-          {:ok, [atom], [warning] | info()} | {:error, [error], [warning] | info()}
+          {:ok, [atom], [warning] | info()}
+          | {:error, [error] | [Code.diagnostic(:error)], [warning] | info()}
   def require(files, options \\ []) when is_list(options) do
     spawn_workers(files, :require, options)
   end

lib/elixir/src/elixir.erl

@@ -118,6 +118,7 @@ config_change(_Changed, _New, _Remove) ->
   ok.
 
 set_stdio_and_stderr_to_binary_and_maybe_utf8() ->
+  %% TODO: Remove me once we require Erlang/OTP 26+
   ok = io:setopts(standard_io, [binary, {encoding, utf8}]),
   ok = io:setopts(standard_error, [{encoding, utf8}]),
   ok.