Update the userdoc for the deprecated --namespace option

Co-authored-by: Bence Magyar <bence.magyar.robotics@gmail.com>

controller_manager/doc/userdoc.rst

@@ -158,7 +158,7 @@ There are two scripts to interact with controller manager from launch files:
  -p PARAM_FILE, --param-file PARAM_FILE
  Controller param file to be loaded into controller node before configure
  -n NAMESPACE, --namespace NAMESPACE
- Namespace for the controller_manager and the controller(s) (deprecated)
+ DEPRECATED Namespace for the controller_manager and the controller(s)
  --load-only Only load the controller and leave unconfigured.
  --inactive Load and configure the controller, however do not activate them
  -u, --unload-on-kill Wait until this application is interrupted and unload controller