chore(docs): Update 2-retrieving-data-as-objects.md (#503)

Querying of ObjectObservables is useful. At least the docs should reflect the actual API :~)

Author: ggranum

docs/2-retrieving-data-as-objects.md

@@ -179,7 +179,9 @@ this.item.subscribe(snapshot => {
 ```
 
 ## Querying?
-The `FirebaseObjectObservable` synchronizes objects from the realtime database. There is no querying available for objects because 
-objects are simply JSON, and JSON order is specified by the browser.
+
+Because `FirebaseObjectObservable` synchronizes objects from the realtime database, sorting will have no effect for queries that are not also limited by a range. For example, when paginating you would provide a query with a sort and filter. Both the sort operation and the filter operation affect which subset of the data is returned by the query; however, because the resulting object is simply json, the sort order will not be preseved locally. Hence, for operations that require sorting, you are probably looking for a [list](3-retrieving-data-as-lists.md)
+
+For filtering response data see [](4-querying-lists.md) and repeat 'Object' to yourself everytime you read the word 'List'. 
 
 ###[Next Step: Retrieving data as lists](3-retrieving-data-as-lists.md)