add Code Overview section for better clarity

Author: yarnabrina

examples/clients/simple-sampling-client/README.md

@@ -43,5 +43,6 @@ You will be prompted to enter a message. Type your message and press Enter. The
 
 Type `exit` or `quit` to stop the client.
 
----
+## Code Overview
+
 For more details, see the source code in `mcp_simple_sampling_client/main.py`.