docs: link README.de.md in English Quick Links section

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: TimInTech

README.md

@@ -20,6 +20,7 @@
 - Simulation Guide: [SIMULATION.md](SIMULATION.md)
 - Bedrock Networking: [docs/BEDROCK_NETWORKING.md](docs/BEDROCK_NETWORKING.md)
 - Copilot Workflow: [.github/copilot-instructions.md](.github/copilot-instructions.md)
+- 🇩🇪 Deutsche Version: [README.de.md](README.de.md)
 - Issues — <https://github.com/TimInTech/minecraft-server-Proxmox/issues>
 
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