Reporting taxonomy value update: ms.service = functions -> azure-functions

Please see attached spreadsheet for **azure-docs-sdk-java** usage of the ms.service reporting taxonomy value **functions,** which should be removed and replaced with the ms.service reporting taxonomy value **azure-functions [functions_to_azure-functions.xlsx](https://github.com/Azure/azure-docs-sdk-dotnet/files/13866775/functions_to_azure-functions.xlsx) ** Please Assign to: - **Daniel Jurek ([@danieljurek](https://github.com/danieljurek))** With the Label: - **Docs**