List all status values in status filter documentation

Signed-off-by: Patrick Koenig <pkoenig10@gmail.com>

libpod/define/containerstate.go

@@ -89,6 +89,8 @@ func StringToContainerStatus(status string) (ContainerStatus, error) {
 		return ContainerStateExited, nil
 	case ContainerStateRemoving.String():
 		return ContainerStateRemoving, nil
+	case ContainerStateStopping.String():
+		return ContainerStateStopping, nil
 	default:
 		return ContainerStateUnknown, fmt.Errorf("unknown container state: %s: %w", status, ErrInvalidArg)
 	}