doc: add Dell PowerEdge R440 to tested devices

Author: jenningsloy318

README.md

@@ -98,7 +98,7 @@ Note that port 9610 has been [reserved][4] for the redfish_exporter.
 ## Supported Devices (tested)
 - Lenovo ThinkSystem SR850 (BMC 2.1/2.42)
 - Lenovo ThinkSystem SR650 (BMC 2.50)
-
+- PowerEdge R440 
 ## Acknowledgement
 
 - [gofish][5] provides the underlying library to interact servers