docs(readme): mark Unit 2 WebSocket chat as complete

Author: gsinghjay

README.md

@@ -9,7 +9,7 @@ This project aims to build a functional real-time chat application enhanced with
 This project is broken down into the following units. See each unit's README for details:
 
 1.  **[Unit 1: RAG Fundamentals & Basic Demo](assignment1_llm_embeddings/README.md)** - ✅ Complete! Basic RAG implementation with document processing, embedding generation, and query answering. ([See demo output](RAG-output.md))
-2.  **[Unit 2: Real-Time WebSocket Chat](assignment2_websocket_chat/README.md)** - Builds the foundational real-time chat server and client.
+2.  **[Unit 2: Real-Time WebSocket Chat](assignment2_websocket_chat/README.md)** - ✅ Complete! Built a functional real-time chat server and client with Socket.IO. ([See demo output](websockets-example.png))
 3.  **[Unit 3: Integrating RAG with Real-Time Chat](assignment3_rag_chat_integration/README.md)** - (TBA) Focuses on combining RAG (Unit 1) with the chat system (Unit 2).
 4.  **[Unit 4: Advanced RAG Techniques & Optimization](assignment4_advanced_rag/README.md)** - (TBA) Explores improvements to the RAG pipeline.
 5.  **[Unit 5: User Interface Enhancements](assignment5_ui_ux/README.md)** - (TBA) Focuses on improving the chat UI/UX.