[prototype] Add case description for prototype demonstration

@DennisGlaeser Can you add a description for Benchmark case 1 by editing this file: https://git.iws.uni-stuttgart.de/dumux-appl/dumux-web-app/-/blob/master/services/server/flask-backend/static/data/simulation-2.md?

The current idea:

• description (the about tab) only describes the case setup boundary conditions and domain
• the set parameter tab let's you change parameters; every form element (dropdown menu, slider, checkbox,...) has an info sign next to it with a popover opening on click or hover (see #6 (closed)) that explains what that specific parameter changes in the setup.