Add AdGuard Home installation and configuration tutorials for Raspberry Pi

- Created German and English markdown files for the AdGuard Home installation tutorial on Raspberry Pi.
- Added detailed step-by-step instructions for setting up AdGuard Home, including video links and troubleshooting notes.
- Created German and English markdown files for the basic configuration of AdGuard Home post-installation.
- Included recommendations for blacklists and trusted DNS servers in both configuration tutorials.

Author: marci