Add capability to turn off children error message and make note of this in Conf user guide/admin guide docs

A customer was complaining about the error message that appears in Confluence if the user does not have permissions to view the content included via the children macro. As such, can we please add a flag to the children macro so that the error message can be turned off so that the page will render seamlessly (with no error messages) regardless of the children macro existing and the viewers permissions.
We also need to make note of this in the Confluence documentation - in the user guide I'd suggest.