Fixed typo in Enum docs

Author: jwarwick

lib/elixir/lib/enum.ex

@@ -864,7 +864,7 @@ defmodule Enum do
   @doc """
   Splits the enumerable into two collections, leaving `count`
   elements in the first one. If `count` is a negative number,
-  it starts couting from the back to the beginning of the
+  it starts counting from the back to the beginning of the
   collection.
 
   Be aware that a negative `count` implies the collection