Update genai-on-vertex-ai/gemini_2_0/gemini-multimodal-live-api-dev-g…

…uide/part_3_vertex_api/README.md

Co-authored-by: code-review-assist[bot] <182814678+code-review-assist[bot]@users.noreply.github.com>

genai-on-vertex-ai/gemini_2_0/gemini-multimodal-live-api-dev-guide/part_3_vertex_api/README.md

@@ -115,4 +115,10 @@ Each chapter builds upon its Part 2 counterpart while handling Vertex AI specifi
 - Authentication with Vertex AI
 - WebSocket connection management
 - Message routing
-- Token refresh and session management 
+Each chapter builds upon its Part 2 counterpart while handling Vertex AI specifics. The proxy server handles:
+- Authentication with Vertex AI
+- WebSocket connection management
+- Message routing
+- Token refresh and session management
+
+The proxy server enhances security by handling authentication and token management on the backend, preventing exposure of sensitive credentials on the client-side. It also maintains persistent connections and handles reconnection logic, improving the reliability of the application.