Make use of demo server

[Pfeil]

I'd like to include instructions for the demo server instead of requiring a local setup. Not sure how it will look like in the end.

• Update mdbook and CI mdbook version. It is a static generator and there will be no security issues, but it is probably not a bad idea to take small steps than one larger at a later point.
• Appendix: Update FAIR DO Lab page and reference the Demo server somehow.
• Appendix: Remove outdated information, prefer referencing the webpage/portfolio and the git repositories, as they are usually more up-to-date.
• Update the recipes to make use of the demo instance. The appendix has the references about how to set it up on your own.
• Include Information how the demo servers Typed PID Maker is being used somehow.
• Consider adding recipes about the user interfaces on the demo server.