Update private-endpoint-overview.md

Added PostgreSQL Flexible Server to the Documentation

Author: AbdullahBell

articles/private-link/private-endpoint-overview.md

@@ -88,6 +88,7 @@ A private-link resource is the destination target of a specified private endpoin
 | Azure Database for MySQL - Single Server | Microsoft.DBforMySQL/servers | mysqlServer |
 | Azure Database for MySQL- Flexible Server | Microsoft.DBforMySQL/flexibleServers | mysqlServer |
 | Azure Database for PostgreSQL - Single server | Microsoft.DBforPostgreSQL/servers | postgresqlServer |
+| Azure Database for PostgreSQL - Flexable server | Microsoft.DBforPostgreSQL/flexibleServers | postgresqlServer |
 | Azure Databricks | Microsoft.Databricks/workspaces | databricks_ui_api, browser_authentication |
 | Azure Device Provisioning Service | Microsoft.Devices/provisioningServices | iotDps |
 | Azure Digital Twins | Microsoft.DigitalTwins/digitalTwinsInstances | API |