chore: Update README.md (#2132)

Author: maninhill

README.md

@@ -1,5 +1,6 @@
 <p align="center"><img src= "https://github.com/1Panel-dev/maxkb/assets/52996290/c0694996-0eed-40d8-b369-322bf2a380bf" alt="MaxKB" width="300" /></p>
 <h3 align="center">Ready-to-use, flexible RAG Chatbot.</h3>
+<h3 align="center">基于大模型和 RAG 的开源知识库问答系统.</h3>
 <p align="center"><a href="https://trendshift.io/repositories/9113" target="_blank"><img src="https://trendshift.io/api/badge/repositories/9113" alt="1Panel-dev%2FMaxKB | Trendshift" style="width: 250px; height: 55px;" width="250" height="55"/></a></p>
 <p align="center">
   <a href="https://www.gnu.org/licenses/gpl-3.0.html#license-text"><img src="https://img.shields.io/github/license/1Panel-dev/maxkb?color=%231890FF" alt="License: GPL v3"></a>