Add documentation to xios_print_file option

Author: oakleybrunt

documentation/source/developer_guide/lfric_apps_rose_stem/adding_new_test.rst

@@ -199,6 +199,10 @@ The table below shows a list of possible entries for ``task_dict`` in the task d
      - Int
      - 0
      - Controls the level of information that XIOS logs to stdout. Used to set the ``info_level`` within xml files.
+   * - xios_print_file
+     - Str
+     - "false"
+     - Controls whether XIOS creates ``xios_<client/server>_<rank>.out`` and ``xios_<client/server>_<rank>.err`` files. If ``xios_info_level`` is greater than 5, ``xios_print_file`` will be set to "true".
    * - example_dir
      - Str
      - "example"