[8.5][DOCS] Adds ML-related highlights to 8.5 (#90506)

Co-authored-by: David Roberts <[email protected]>
Co-authored-by: Lisa Cawley <[email protected]>

Author: 3 people

docs/reference/release-notes/highlights.asciidoc

@@ -102,6 +102,32 @@ coarse time resolution, is also supported.
 
 {es-pull}90116[#90116]
 
-// end::notable-highlights[]
+[discrete]
+[[unattended_mode_for_transforms]]
+=== Unattended mode for transforms
+
+The new `unattended` setting for transforms introduces unattended mode. It
+enables the transform to retry indefinitely, even in the face of errors that 
+require direct intervention to resolve. For example, a high disk watermark may
+prevent all ingest activities, including the indexing operation of a transform;
+however once the original issue is resolved by the system administrator, the
+transform automatically continues to operate from where it stopped working.
+Neither the system administrator nor the end-user need to restart the transform.
+
+{es-pull}89212[#89212]
+
+[discrete]
+[[frequent-items-agg]]
+=== Frequent items aggregation
+
+The 
+{ref}/search-aggregations-bucket-frequent-items-aggregation.html[frequent items aggregation] 
+is a new bucket aggregation which identifies items that often occur together. It
+is a form of association rule mining that helps to discover relationships
+between different data points. For example, the aggregation can find attributes
+of log events that tend to co-occur and may give a more informative explanation
+for the possible causes of a spike in the logs.
 
+{es-pull}83055[#83055]
 
+// end::notable-highlights[]