Update installation guide

[Flo0807]

Installation guide should be updated.

see #399 and #398

• [x] Mention Alpinejs in prerequisites
• [x] Mention prerequisites in installation guide
• [x] Note that@tailwindcss/forms plugin can lead to styling issues (describe how to use strategy: 'class' approach)
• [x] Note that background colors on body-tag should be removed
• [x] Adjust deps folder path in tailwind.config.js
• [ ] ~Explain workaround for Heroicons plugin approach~ see https://github.com/naymspace/backpex/issues/401
• [x] Note to daisyui light mode