Update ADK doc according to issue #63 - 4

Author: adk-bot

docs/a2a/index.md

@@ -19,4 +19,17 @@ Navigate through the guides below to learn about ADK's A2A capabilities:
   [**Official Website for Agent2Agent (A2A) Protocol**](https://a2a-protocol.org/)
 
   The official website for A2A Protocol.
-  
+
+## A2A Logging
+
+ADK provides detailed, structured logging for A2A requests and responses to help with debugging and monitoring multi-agent interactions. When you enable logging in your ADK application, the A2A communications will be automatically logged with a clear and easy-to-read format.
+
+The logs include:
+
+*   **Request and Response Details:** Information about the message, such as message ID, role, task ID, and context ID.
+*   **Message Parts:** The content of each part of the message, with a summary for large data parts.
+*   **Metadata:** Any metadata associated with the message or task.
+*   **Status Messages:** The status of the task, including state and any status messages.
+*   **History:** A summary of the conversation history.
+
+These structured logs make it easier to trace the flow of communication between agents and understand the state of each agent at different points in time.