README.md in avromatic-0.10.0.rc1 vs README.md in avromatic-0.10.0

@@ -39,10 +39,14 @@
   `Avro::Schema` objects. See [Models](#models).
 * **nested_models**: An optional [ModelRegistry](https://github.com/salsify/avromatic/blob/master/lib/avromatic/model_registry.rb)
   that is used to store, by full schema name, the generated models that are
   embedded within top-level models. By default a new `Avromatic::ModelRegistry`
   is created.
+* **on_initialize**: An optional Proc that runs at the end of
+  `Avromatic.configure` and during code reloading in Rails applications. This
+  option is useful for defining models that will be extended when the load
+  order is important.
 
 #### Using a Schema Registry/Messaging API
  
 The configuration options below are required when using a schema registry 
 (see [Confluent Schema Registry](http://docs.confluent.io/2.0.1/schema-registry/docs/intro.html))
@@ -167,12 +171,22 @@
 it can be used as a nested model.
 
 To extend a model that will be used as a nested model, you must ensure that it
 is defined, which will register it, prior it being referenced by another model.
 
-With Rails for example, it may be necessary to reference in an initializer
-models that are extended and will be used as nested models so that classes load
-in the correct order.
+Using the `Avromatic.on_initialize` option allows models that are extended and
+will be used as nested models to be defined at the end of the `.configure`
+block. In Rails applications, this Proc will also be executed after
+`nested_models` is cleared when code reloads to ensure that classes load in the
+correct order:
+
+```ruby
+Avromatic.configure do |config|
+  config.on_initialize do
+    # reference any extended models that should be defined first
+    MyNestedModel
+  end
+end
 
 #### Custom Types
 
 Custom types can be configured for fields of named types (record, enum, fixed).
 These customizations are registered on the `Avromatic` module. Once a custom type