[Enhancement] - Document how to use Visual Studio Code for add-on development using openHAB inside a docker container.

[pgfeller]

During the work on the huesync binding I learned that it is very convenient to use a docker container with a openHAB instance to debug the binding you're working on.

This allows you to work on a development machine without the need to install openHAB directly on it (I do not want/need it on that device). It also allows you to work next to a productive instance and/or update/reset/change the server environment easely.

The setup is simple - but still requires some knowledge - therefore I propose to add information about this possibility and how to set it up to VSCode.

I could update the documentation during my work on the binding if you would like to have this. @stefan-hoehn ➡️ In that case you can assign this issue to me.

[stefan-hoehn]

I looked into our docs where this would probably fit best.

IMHO, the place to put it would be

https://next.openhab.org/docs/developer/#setup-the-development-environment

where a also found an issue we could improve: if you click on one of the IDEs, ie. VSCODE it forwards you to

https://next.openhab.org/docs/developer/ide/vscode.html

which could never be reached nor found via the menu on the left.

With the new submenu option like in

we should add these as well first:

I would then first provide a PR for that. WDYT?