Experimental advertising for Citus

Author: jonels-msft

articles/cosmos-db/includes/appliesto-postgresql.md

@@ -10,4 +10,5 @@ ms.date: 09/01/2022
 
 APPLIES TO:
 :::image type="icon" source="media/applies-to/yes-icon.svg" border="false":::
-PostgreSQL
+Azure Cosmos DB for PostgreSQL (powered by the [Citus database
+extension](https://github.com/citusdata/citus) to PostgreSQL)