Add zettelkasten to README.md (#2718)

* Update README.md


## Add Zettelkasten MCP Server

This PR adds the Zettelkasten to the community servers list.

### Project Overview
Comprehensive AI-powered knowledge management system that implements the proven Zettelkasten (slip-box) method with modern AI assistance.

### Key Features
- **Atomic Note Management**: Create, organize, and connect atomic ideas
- **AI-Powered Workflows**: CEQRC process for enhanced learning
- **Full-Text Search**: SQLite FTS5 with advanced query syntax
- **Intelligent Linking**: AI-suggested connections between notes
- **Multiple Interfaces**: CLI, REST API, Streamlit UI, and MCP server
- **Comprehensive Documentation**: Setup guides and examples included

### MCP Server Details
- **Transport**: STDIO
- **Tools**: 7 comprehensive tools for note management and AI workflows
- **Dependencies**: OpenAI API (optional, has stub mode)
- **Python**: 3.11+ with modern async/await patterns
- **Setup**: Automated setup script with Claude Desktop config generation

### Repository Information
- **URL**: https://github.com/joshylchen/zettelkasten
- **License**: MIT
- **Documentation**: Complete setup guide in `docs/MCP_SETUP.md`
- **Tests**: Comprehensive test coverage included

This server demonstrates sophisticated MCP patterns and provides real value for knowledge workers and researchers using AI assistants.

* update Zettelkasten under community project

README.md

@@ -1268,6 +1268,7 @@ A growing set of community-developed and maintained servers demonstrates various
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 - **[ZapCap](https://github.com/bogdan01m/zapcap-mcp-server)** - MCP server for ZapCap API providing video caption and B-roll generation via natural language
+- **[Zettelkasten](https://github.com/joshylchen/zettelkasten)**- Comprehensive AI-powered knowledge management system implementing the Zettelkasten method. Features atomic note creation, full-text search, AI-powered CEQRC workflows (Capture→Explain→Question→Refine→Connect), intelligent link discovery, and multi-interface access (CLI, API, Web UI, MCP). Perfect for researchers, students, and knowledge workers.
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 ## 📚 Frameworks