Update changelog based on model updates

Author: aws-sdk-python-automation

.changes/next-release/api-change-datazone-23603.json

@@ -0,0 +1,5 @@
+{
+  "type": "api-change",
+  "category": "``datazone``",
+  "description": "This release adds support for 1) highlighting relevant text in returned results for Search and SearchListings APIs and 2) returning aggregated counts of values for specified attributes for SearchListings API."
+}

.changes/next-release/api-change-omics-99488.json

@@ -0,0 +1,5 @@
+{
+  "type": "api-change",
+  "category": "``omics``",
+  "description": "Add Git integration and README support for HealthOmics workflows"
+}