docs: add module quickstart matrix to README (#452)

Co-authored-by: however <however-yir@users.noreply.github.com>

Author: however-yir

README.md

@@ -17,3 +17,12 @@
 ## 参与建设
 
 欢迎任何形式的代码贡献。
+
+## Quickstart Matrix (Community Contribution)
+
+| module | purpose | command | required services | env vars |
+|---|---|---|---|---|
+| spring-ai-alibaba-mcp-example | MCP demo | `mvn -pl spring-ai-alibaba-mcp-example spring-boot:run` | none/local mcp tool | model api key |
+| spring-ai-alibaba-rag-example | RAG demo | `mvn -pl spring-ai-alibaba-rag-example spring-boot:run` | vector db (optional by profile) | model api key, embedding model |
+| spring-ai-alibaba-tool-calling-example | tool calling | `mvn -pl spring-ai-alibaba-tool-calling-example spring-boot:run` | none | model api key |
+