Add example for stateless server with JSON response

Author: 5enxia

README.md

@@ -400,6 +400,9 @@ mcp = FastMCP("StatefulServer")
 # Stateless server (no session persistence)
 mcp = FastMCP("StatelessServer", stateless_http=True)
 
+# Stateless server (no session persistence, no sse stream with supported client) 
+mcp = FastMCP("StatelessServer", stateless_http=True, json_response=True)
+
 # Run server with streamable_http transport
 mcp.run(transport="streamable-http")
 ```