add further specification to android notification structure

doc/notifications-structure-android.md

@@ -4,7 +4,10 @@ The current structure of the notification payload on android does not allow for
 
 ## Proposed solution
 
+Replace the notification message with a data message. Documentation on both types can be found [here](https://firebase.google.com/docs/cloud-messaging/concept-options#notifications_and_data_messages)
+
 1. Add the data from the `notification` object to the `data` object.
+2. Put the `data` object on the top level
 2. Remove the `notification` object.
 
 The names of the fields in the `notification` object could be the same in the `data` object. This way the client has to manually handle their notifications, which gives it the liberty to customise the design.