docs: clarify Docker installation requirements and add platform-specific instructions

- Replace "Docker Desktop" prerequisite with generic "Docker installed"
- Add detailed Docker installation instructions for macOS, Linux, and Windows
- Include package manager options (Homebrew, apt-get, winget, Chocolatey)
- Add Docker verification command
- Update related documentation files for consistency
- Use collapsible section to keep Quick Start clean

Now users understand they can use any Docker installation method, not just Docker Desktop.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

docs/README_CLAUDE_SETUP.md

@@ -6,7 +6,7 @@ This guide helps you connect n8n-MCP to Claude Desktop, giving Claude comprehens
 
 - Claude Desktop installed
 - For local installation: Node.js (any version)
-- For Docker: Docker Desktop or Docker Engine
+- For Docker: Docker installed (see installation instructions in main README)
 
 ## 🛠️ Configuration Methods