doc: Add DeepWiki badge in README

Author: observerw

README.md

@@ -2,6 +2,7 @@
 
 [![Python](https://img.shields.io/badge/Python-3.12+-blue.svg)](https://python.org)
 [![License](https://img.shields.io/badge/License-MIT-green.svg)](LICENSE)
+[![Ask DeepWiki](https://deepwiki.com/badge.svg)](https://deepwiki.com/observerw/lsp-client)
 
 A full-featured, well-typed, and easy-to-use Python client for the Language Server Protocol (LSP). This library provides a clean, async-first interface for interacting with language servers, supporting both local and Docker-based runtimes.