Add warning that aggregated request metric data format may yet change.
@@ -106,3 +106,7 @@ New Features
giving access to aggregrated metrics over the time of a reporting period.
This includes bucketed time data on requests so can calculate distribution
of server, queue and application time.
+
+ Note that the new request metrics is still a work in progress and may be
+ modified or enhanced, causing breaking changes in the format of data
+ returned.
