Add complete documentation for the Phoenix Sink

Greetings,

This is the documentation that was to be added for this whole new Vis/Phoenix application. I think it is complete and I wrote everything that there is to know about it.

The only thing that is left for this whole application to be complete, is the qmtest check for the json file data output in the Moore project, but as this will be a separate MR and independent from this one, even though I marked it as Draft, I think it's ready to go.

Please Mr. @sponce do have a look and review it for mistakes and let me know for fixes that you might want me to do, so I can mark it as ready to go!

Thank you!