warn users to place comments outside custom stuff

[Dan Jacobson]

I comment out some lines in the (custom-set-faces) part of my .emacs
file.

My comments got deleted the next time I entered the wonderful menu
driven customization system.

Therefore, the warning
  ;; custom-set-faces was added by Custom -- don't edit or cut/paste it!
  ;; Your init file should contain only one such instance.
should be revised to
  ;; custom-set-faces was added by Custom -- don't edit or cut/paste it!
  ;; Your init file should contain only one such instance.
  ;; Place all comments outside this section or else they will
  ;; likely be deleted!