Add @doc since: "1.12.0" and comments (#11046)

Author: TORIFUKUKaiou

lib/elixir/lib/io.ex

@@ -516,6 +516,7 @@ defmodule IO do
       IO.stream(:stdio, :line)
 
   """
+  @doc since: "1.12.0"
   def stream, do: stream(:stdio, :line)
 
   @doc """
@@ -534,6 +535,9 @@ defmodule IO do
   Note that an IO stream has side effects and every time
   you go over the stream you may get different results.
 
+  `stream/1` has been introduced in Elixir v1.12.0,
+  while `stream/2` has been available since v1.0.0.
+
   ## Examples
 
   Here is an example on how we mimic an echo server
@@ -557,6 +561,7 @@ defmodule IO do
       IO.binstream(:stdio, :line)
 
   """
+  @doc since: "1.12.0"
   def binstream, do: binstream(:stdio, :line)
 
   @doc """
@@ -574,6 +579,9 @@ defmodule IO do
 
   Finally, do not use this function on IO devices in Unicode
   mode as it will return the wrong result.
+
+  `binstream/1` has been introduced in Elixir v1.12.0,
+  while `binstream/2` has been available since v1.0.0.
   """
   @spec binstream(device, :line | pos_integer) :: Enumerable.t()
   def binstream(device \\ :stdio, line_or_bytes)