knigge: Update moduledoc to fix a reference to Application.put_env

lib/knigge.ex

@@ -132,7 +132,7 @@ defmodule Knigge do
 
   By default `Knigge` does as much work as possible at compile time. This will
   be fine most of the time. In case you want to swap out the implementation at
-  runtime - by calling `Application.put_env/2` - you can force `Knigge` to do all
+  runtime - by calling `Application.put_env/3` - you can force `Knigge` to do all
   delegation at runtime. As you might expect this incurs runtime overhead,
   since the implementing module will have to be loaded for each call.