Mention flags in the intro

Author: jbaiera

manage-data/data-store/data-streams/failure-store.md

@@ -6,7 +6,9 @@ applies_to:
 
 # Failure store [failure-store]
 
-Failure stores are a secondary set of indices inside a data stream dedicated to storing failed documents. Failed documents are any documents that cause ingest pipeline exceptions or have a structure that conflicts with a data stream's mappings. These failures normally cause the indexing operation to fail, returning the error message in the response. When a data stream's failure store is enabled, these failures are instead captured in a separate index and persisted to be analysed later, returning a successful response to the client in the meantime. Failure stores do not capture failures caused by backpressure or document version conflicts. These failures are always returned as-is since they warrant specific action by the client.
+Failure stores are a secondary set of indices inside a data stream dedicated to storing failed documents. Failed documents are any documents that cause ingest pipeline exceptions or have a structure that conflicts with a data stream's mappings. These failures normally cause the indexing operation to fail, returning the error message in the response. 
+
+When a data stream's failure store is enabled, these failures are instead captured in a separate index and persisted to be analysed later. Clients receive a successful response with a flag indicating the failure was redirected. Failure stores do not capture failures caused by backpressure or document version conflicts. These failures are always returned as-is since they warrant specific action by the client.
 
 ## Set up a data stream failure store [set-up-failure-store]