docs: polish README and add optimized MCP integration image

- Improve grammar and sentence structure in MCP section
- Add proper markdown image formatting with relative paths
- Optimize mcp_leann.png size (1.3MB -> 224KB)
- Update data description to be more specific about Chinese content

packages/leann-mcp/README.md

@@ -30,7 +30,7 @@ claude mcp add leann-server -- leann_mcp
 
 ```bash
 # Build an index for your project
-leann build my-project
+leann build my-project --docs ./ #change to your doc PATH
 
 # Start Claude Code
 claude