Update Settings.cs

Error displayed is misleading for those who have a custom set.

PoGo.NecroBot.Logic/Settings.cs

@@ -220,7 +220,7 @@ private void SetDevInfoByKey(string devKey)
             }
             else
             {
-                throw new ArgumentException("Invalid device info package! Check your auth.config file and make sure a valid DevicePackageName is set or simply set it to 'random'...");
+                throw new ArgumentException("Invalid device info package! Check your auth.config file and make sure a valid DevicePackageName is set. For simple use set it to 'random'. If you have a custom device set it to 'custom'.");
             }
         }
     }