Clarify migration risks

@FinVamp1 @nzthiago does this work?

Author: ggailey777

articles/azure-functions/functions-how-to-use-azure-function-app-settings.md

@@ -139,6 +139,8 @@ You can use either the Azure portal or Azure CLI commands to migrate a function
 + Migration isn't supported on Linux. 
 + The source plan and the target plan must be in the same resource group and geographical region. For more information, see [Move an app to another App Service plan](../app-service/app-service-plan-manage.md#move-an-app-to-another-app-service-plan).
 + The specific CLI commands depend on the direction of the migration.
++ Downtime in your function executions occur as the function app is migrated between plans.
++ State and other app-specific content is maintained, since the same Azure Files share is used by the app both before and after migration.
 
 ### Migration in the portal