Update relase notes

3.0-RELEASE-NOTES.md

@@ -127,3 +127,12 @@ removed properties together with the middleware module name to use instead:
 We have also removed `loopback.mime`, which was always set to `undefined`.
 
 See [loopback#2349](https://github.com/strongloop/loopback/pull/2394).
+
+## Remove sugar for creating models
+
+`app.model(modelName, settings)`, a sugar for creating non-existing model, is
+now removed in favor of promoting use of:
+- `app.registry.createModel(modelName, properties, options) to create new model
+- `app.model(modelCtor, config)` to update existing model and attach it to app
+
+Please see [related code change](https://github.com/strongloop/loopback/pull/2401) here.