added known issue (#4349)

changelog.md

@@ -1317,6 +1317,7 @@ Below is a list of any know issues affecting the [recommended minimum version](#
 
 | Issue | Impact | Mitigation | Tracking link |
 | --- | --- | --- | --- |
+| `FeedIterator` enters an infinite loop after a physical partition split occurs in a container using hierarchical partition keys. | Queries using prefix partition keys.  | Rather than having the PK included in the query request options, filtering on top level hierarchical Pks should be done through where clauses. | [#4326](https://github.com/Azure/azure-cosmos-dotnet-v3/issues/4326) | 
 
 ## Release & Retirement dates