Ambiguosity in iterating over list

[Jacob Lee]

This is a minor documentation issue, but it did send me down the wrong
path for a little while.

The tutorial says that iteration can be used in the following contexts:
    * in the `to' field of a multiple link action,
    * in the `from' field of a copy action,
    * in the directory field of a tidy action,
    * in the directory field of the files action,
    * in the ignore action,
    * in a shell command.

And the reference manual says:
    * in the `to' field of a multiple link action,
    * in the `from' field of a copy action,
    * in the directory field of a tidy action,
    * in the directory field of the files action,
    * in the ignore action.

It has been my experience that iterating over a list does not work in
the shellcommands section, contrary to the tutorial's statement. This
led me to try to do "/sbin/chkconfig --level 2345 $(services_on)" where
services_on looks like "cups:ssh:cfenvd...(etc)". Creating a separate
shell script did fix the problem, but it still would be good to update
the tutorial.

Thanks