DOC-28 add cluster message hierarchy diagram (#934)

Author: Deflaimun

modules/manage/pages/cluster-maintenance/disk-utilization.adoc

@@ -167,6 +167,8 @@ Redpanda supports group offset deletion with the Kafka OffsetDelete API through
 
 The `log_segment_size` property specifies the size of each log segment within the partition. Redpanda closes segments after they exceed this size and messages begin filling a new segment.
 
+image::shared:cluster-message-retention.png[Cluster message retention hierarchy]
+
 To set `log_segment_size`:
 
 [,bash]