Feedback for webpage

[maurerle]

I still got the following feedback to the current energy system webpage

• Add a simplified feature status table (Implemented/WIP/Planned)
• Add PyPI badges or project health indicators
• Add the missing RL Algorithm tutorial link (04a notebook)
• Consider a "Who is it made for?" blurb on the homepage
• Add contact@assume-project.de as a general contact option
• Consider adding past workshop information