Update README

Author: Justin Wood

README.md

@@ -16,16 +16,15 @@ or check out examples below.
 ```elixir
 # In your config/config.exs file
 config :my_app, Repo,
+  adapter: Mongo.Ecto
   database: "ecto_simple",
   username: "mongodb",
   password: "mongosb",
   hostname: "localhost"
 
 # In your application code
 defmodule Repo do
-  use Ecto.Repo,
-    otp_app: :my_app,
-    adapter: Mongo.Ecto
+  use Ecto.Repo, otp_app: :my_app
 end
 
 defmodule Weather do