Added kwargs description to add_process docstring

Author: kzscisoft

simvue/run.py

@@ -653,7 +653,7 @@ def callback_function(status_code: int, std_out: str, std_err: str) -> None:
             this trigger event is set when the processes completes
         env : typing.Dict[str, str], optional
             environment variables for process
-        **kwargs
+        **kwargs : Any, ..., optional
             all other keyword arguments are interpreted as options to the command
         """
         if platform.system() == "Windows" and completion_callback: