add mcp module in the readme

Author: goldmedal

README.md

@@ -82,10 +82,11 @@ https://github.com/user-attachments/assets/dab9b50f-70d7-4eb3-8fc8-2ab55dc7d2ec
 Wren Engine is currently in the beta version. The project team is actively working on progress and aiming to release new versions at least biweekly.
 
 ## 🛠️ Developer GuideS
-The project consists of three main modules:
-1. [ibis-server](./ibis-server/): the Python web server powered by FastAPI and Ibis
+The project consists of 4 main modules:
+1. [ibis-server](./ibis-server/): the Web server of Wren Engine powered by FastAPI and Ibis
 2. [wren-core](./wren-cores): the semantic core written in Rust powered by [Apache DataFusion](https://github.com/apache/datafusion)
 3. [wren-core-py](./wren-core-py): the Python binding for wren-core
+4. [mcp-server](./mcp-server/): the MCP server of Wren Engine powered by [MCP Python SDK](https://github.com/modelcontextprotocol/python-sdk)
 
 ## ⭐️ Community