Describe correlation feature

Author: dmpop

trento/adoc/trento-activity-log.adoc

@@ -67,3 +67,19 @@ This can be changed in the Activity Log section under Settings. Changing
 the retention time requires the `+all:settings+` permissions. Entries
 older than the specified retention time are deleted every day at
 midnight (UTC timezone).
+
+The correlation functionality of the Activity Log links related events together,
+offering a chronological, linear view of a chain of events in a multi-step workflows
+triggered by a user action.
+
+For example, the host clean-up operation de-registers the database
+instance, de-registers the database itself, and then de-registers the host.
+All these entires are displayed chronologically, when you view the host clean
+up entry in the Activity Log.
+
+The following categories of Activity Log entries are linked together:
+
+. entries caused by de-registration of hosts
+. entries caused by API key re-generation
+. entries caused by SMLM settings save/update
+. entries caused by host and cluster operations