Use Ecto 2.0.1

ecto.md

@@ -33,7 +33,7 @@ To add Ecto to this application, there are a few steps that we need to take. The
 ```elixir
 defp deps do
   [
-    {:ecto, "2.0.0-beta.2"},
+    {:ecto, "2.0.1"},
     {:postgrex, "0.11.1"}
   ]
 end