V3 Return style attributes about azure-functions-fsharp-examples

[Youenn-Bouglouan]

@sadgit if you also want to do more complex things in the function body (for instance respond to an HTTP request), you can also use the IAsyncCollector class.
See example in the PR here #5

[sadgit]

I have been having some issues with the Microsoft.Azure.ServiceBus 4.1.3 - which is happy with the return Attribute but didn't want to respect old style (v2) Async Collector.
This also causes complication of HTTP triggers and multiple output Queues.
Our codebase is fine - but I wanted to keep these examples current as I found them useful.