gfile: Document usefulness of g_file_dup()
gfile: Document usefulness of g_file_dup()

Signed-off-by: Philip Withnall <withnall@endlessm.com>

https://gitlab.gnome.org/GNOME/glib/issues/807

endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib