Remove accordion from FAQ

In VC 2022-11-23 it was decided to remove accordion altogether and discuss a possible re-implementation later when having more content.

• search works now
• linking works now, e.g. this one

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• Add TOC
  • corrected jumps to anchors
• More spacing between subsequent Q&A
• _optional: add short tags to some (AAI) questions
• it was discussed to also fully revert to markdown. @lisa.klaffki @erxleb87 what was the motivation to change from markdown content (within html brackets) to full html in the first place?. Decide to not change back to MD without need.