Amazon OpenSearch Service Update: Improve descriptions for various API commands and data types.

Author: AWS

.changes/next-release/feature-AmazonOpenSearchService-7a485f6.json

@@ -0,0 +1,6 @@
+{
+    "type": "feature",
+    "category": "Amazon OpenSearch Service",
+    "contributor": "",
+    "description": "Improve descriptions for various API commands and data types."
+}