README.md in carrierwave-mongoid-0.1.4 vs README.md in carrierwave-mongoid-0.1.5

@@ -66,8 +66,18 @@
 end
 ```
 
 ## Known issues and limitations
 
-Note that files mounted in embedded documents aren't saved when parent documents are saved.
-You must explicitly call save on embedded documents in order to save their attached files.
+Note that files mounted in embedded documents aren't saved when parent documents
+are saved. By default, mongoid does not cascade callbacks on embedded
+documents. In order to save the attached files on embedded documents, you must
+either explicitly call save on the embedded documents or you must configure the
+embedded association to cascade the callbacks automatically. For example:
+
+```ruby
+class User
+  embeds_many :pictures, cascade_callbacks: true
+end
+```
+
 You can read more about this [here](https://github.com/jnicklas/carrierwave/issues#issue/81)