Adds dnsConfiguration property to the list of deprecated settings for Flex Consumption

Author: sidkri

articles/azure-functions/functions-app-settings.md

@@ -973,6 +973,7 @@ In the [Flex Consumption plan](./flex-consumption-plan.md), these site propertie
 | `WEBSITE_VNET_ROUTE_ALL` |Not used for networking in Flex Consumption|
 | `properties.alwaysOn` |Not valid|
 | `properties.containerSize` |Renamed as `instanceMemoryMB`|
+| `properties.dnsConfiguration` | Custom DNS servers configured in the Azure Virtual Network are automatically used|
 | `properties.ftpsState` | FTPS not supported | 
 | `properties.isReserved` |Not valid|
 | `properties.IsXenon` |Not valid|