External File output binding update

Hi, according to this [reply](https://stackoverflow.com/questions/44734460/corrupt-file-when-using-azure-functions-external-file-binding/44734647#44734647) on SO, the `External File` output binding has been deprecated and I couldn't find anything related in the official [documentation](https://docs.microsoft.com/en-us/azure/azure-functions/functions-triggers-bindings#supported-bindings). What is the alternative way now to write files to remote locations such as an SFTP folder? Is it to manually upload a file ourselves?

_Note_: I've also posted a [question on SO](https://stackoverflow.com/questions/58415948/upload-file-to-sftp-location-from-azure-function)

Start with the official Azure Functions triggers and bindings documentation linked in the issue, then review the referenced Stack Overflow answers and question about SFTP uploads. Clarify whether External File output binding is supported and document the current supported approach for writing to remote locations such as SFTP.

Written by the indexing model from the issue text.