Improve debug-message

Author: bouwew

plugwise_usb/network/__init__.py

@@ -251,7 +251,7 @@ async def node_join_available_message(self, response: PlugwiseResponse) -> bool:
             await self._notify_node_event_subscribers(NodeEvent.JOIN, mac)
             return True
 
-        _LOGGER.debug("Failed to register available Node with mac=%s", mac)
+        _LOGGER.debug("Joining of available Node (%s) failed", mac)
         return False
 
     async def node_rejoin_message(self, response: PlugwiseResponse) -> bool: