Add DeepWiki badge to README

Added a badge for DeepWiki to the README.

Author: feichai0017

README.md

@@ -3,6 +3,7 @@
 [![Crates.io](https://img.shields.io/crates/v/quill-sql.svg)](https://crates.io/crates/quill-sql)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE)
 [![Discord](https://img.shields.io/discord/1458041939587764247?label=Discord&logo=discord&logoColor=white)](https://discord.gg/dJqa4RYW65)
+[![Ask DeepWiki](https://deepwiki.com/badge.svg)](https://deepwiki.com/feichai0017/QuillSQL)
 
 <div align="center">
   <img src="/public/rust-db.png" alt="QuillSQL Architecture" width="720"/>