Update README.md

Add a new dark theme image

Author: khyrulAlam

README.md

@@ -3,7 +3,8 @@ Chat Application using React.JS + Firebase real-time Database + Firebase Gmail A
 
 I build this app for learning purpose. you can check the live 💁‍♂️ [demo](https://chatroom-67e21.web.app/) 
 
-![](https://firebasestorage.googleapis.com/v0/b/chatroom-67e21.appspot.com/o/chat-chat.png?alt=media&token=3ad066ef-e277-4113-a496-e8fa6c110832)
+![image](https://github.com/user-attachments/assets/8d3630ed-b77b-49da-864b-3ef5df6cfbcd)
+
 
 Quick Start:
 ------------
@@ -13,4 +14,4 @@ Quick Start:
 - create a firebase `config.ts` file on /src folder
 - ``` npm install ```
 - ``` npm run dev ```
-- ``` npm run build ```
+- ``` npm run build ```