Updated docs to use __record__(:index) instead of __index__

Author: jwarwick

CHANGELOG.md

@@ -23,6 +23,7 @@
   * [Enum] Receiving the index of iteration in `Enum.map/2` and `Enum.each/2` is deprecated in favor of `Stream.with_index/1`
   * [File] `File.iterator/1` and `File.biniterator/1` are deprecated in favor of `IO.stream/1` and `IO.binstream/1`
   * [File] `File.iterator!/2` and `File.biniterator!/2` are deprecated in favor of `File.stream!/2` and `File.binstream!/2`
+  * [Record] `Record.__index__/2` deprecated in favor of `Record.__record__(:index, key)`
 
 * backwards incompatible changes
   * [Kernel] The `Binary.Inspect` protocol has been renamed to `Inspect`

lib/elixir/lib/kernel.ex

@@ -1517,12 +1517,12 @@ defmodule Kernel do
       #=> [name: nil, age: 0]
 
   In order to quickly access the index of a field, one can use
-  the `__index__` function:
+  the `__record__` function with `:index` as the first argument:
 
-      User.__index__(:age)
+      User.__record__(:index, :age)
       #=> 2
 
-      User.__index__(:unknown)
+      User.__record__(:index, :unknown)
       #=> nil
 
   ## Compile-time introspection