Portals Docs

[jspenger]

There should be some place for docs, where we can collect in-depth information about the project.

A suggestion is to use scaladoc to generate the documentation docs. This also makes sense as we already are using scaladoc for our api docs. The docs should be hosted on https://www.portals-project.org/docs. See for example how we are hosting the api in the api repo.

However, I have not yet succeeded in generating docs. It should be possible, we can look at other examples for this: https://github.com/lampepfl/dotty/tree/main/docs and https://dotty.epfl.ch/.