Add doc about ignore: :whitespace to Base.decode64.

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>

Author: Daniel Perez

lib/elixir/lib/base.ex

@@ -239,10 +239,15 @@ defmodule Base do
   @doc """
   Decodes a base 64 encoded string into a binary string.
 
+  Accepts `ignore: :whitespace` option which will ignore all the
+  whitespace characters in the input string.
+
   ## Examples
 
       iex> Base.decode64("Zm9vYmFy")
       {:ok, "foobar"}
+      iex> Base.decode64("Zm9vYmFy\\n", ignore: :whitespace)
+      {:ok, "foobar"}
 
   """
   @spec decode64(binary) :: {:ok, binary} | :error
@@ -256,13 +261,18 @@ defmodule Base do
   @doc """
   Decodes a base 64 encoded string into a binary string.
 
+  Accepts `ignore: :whitespace` option which will ignore all the
+  whitespace characters in the input string.
+
   An `ArgumentError` exception is raised if the padding is incorrect or
   a non-alphabet character is present in the string.
 
   ## Examples
 
       iex> Base.decode64!("Zm9vYmFy")
       "foobar"
+      iex> Base.decode64!("Zm9vYmFy\\n", ignore: :whitespace)
+      "foobar"
 
   """
   @spec decode64!(binary) :: binary
@@ -290,10 +300,15 @@ defmodule Base do
   Decodes a base 64 encoded string with URL and filename safe alphabet
   into a binary string.
 
+  Accepts `ignore: :whitespace` option which will ignore all the
+  whitespace characters in the input string.
+
   ## Examples
 
       iex> Base.url_decode64("_3_-_A==")
       {:ok, <<255, 127, 254, 252>>}
+      iex> Base.url_decode64("_3_-_A==\\n", ignore: :whitespace)
+      {:ok, <<255, 127, 254, 252>>}
 
   """
   @spec url_decode64(binary) :: {:ok, binary} | :error
@@ -308,13 +323,18 @@ defmodule Base do
   Decodes a base 64 encoded string with URL and filename safe alphabet
   into a binary string.
 
+  Accepts `ignore: :whitespace` option which will ignore all the
+  whitespace characters in the input string.
+
   An `ArgumentError` exception is raised if the padding is incorrect or
   a non-alphabet character is present in the string.
 
   ## Examples
 
       iex> Base.url_decode64!("_3_-_A==")
       <<255, 127, 254, 252>>
+      iex> Base.url_decode64!("_3_-_A==\\n", ignore: :whitespace)
+      <<255, 127, 254, 252>>
 
   """
   @spec url_decode64!(binary) :: binary