Microsoft.web: functionAppConfig property only applies to Flex Consumption

[ffarinha-msft]

The aim of the PR is adding a reference that functionAppConfig property on Microsoft.web only applies to Flex Consumption.

If you try to use it on another Function app sku/tier you get this error:

This is important because adding this detail to the Azure REST API reference will reflect on the Public documentation here https://learn.microsoft.com/en-us/azure/templates/microsoft.web/2024-04-01/sites?pivots=deployment-language-bicep

[openapi-pipeline-app]

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[openapi-pipeline-app]

Generated ApiView

Language	Package Name	ApiView Link
Go	sdk/resourcemanager/appservice/armappservice	There is no API change compared with the previous version
Java	azure-resourcemanager-appservice-generated	https://apiview.dev/Assemblies/Review/a2b80e4fbd144844bca0c504ef8c3337?revisionId=0930b6d5d8de4df6ada1f15279701af6
JavaScript	@azure/arm-appservice	https://apiview.dev/Assemblies/Review/98dbdc8147d7472b9bdff567a8b291bc?revisionId=a7ec3ca84f4242c89de2173479059af4
.Net	Azure.ResourceManager.AppService	There is no API change compared with the previous version