Comma-separated lists of hostnames, etc. in hobbit-alerts.cfg is not documented

["SebA" <spa (at) syntec.co.uk>]

Comma-separated lists of hostnames in hobbit-alerts.cfg is not documented,
so maybe we could add something like this (taken from
http://hobbitmon.sourceforge.net/docs/man5/hobbit-clients.cfg.5.html) to
http://hobbitmon.sourceforge.net/docs/man5/hobbit-alerts.cfg.5.html:

        HOST=targetstring Rule matching a host by the hostname.
"targetstring"
        is either a comma-separated list of hostnames (from the bb-hosts
file),
        "*"  to  indicate "all hosts", or a Perl-compatible regular
expression.
        E.g.  "HOST=dns.foo.com,www.foo.com"  identifies  two  specific
hosts;
        "HOST=%www.*.foo.com  EXHOST=www-test.foo.com" matches all hosts
with a
        name beginning with "www", except the "www-test" host.

Adding an example that used the comma-separated syntax to
http://hobbitmon.sourceforge.net/docs/hobbit-alerts.html and
hobbit-alerts.cfg (sample) files would also be good.

And, actually, maybe something to say that the comma-separated syntax can be
used in all XXX= places (except, presumably, REPEAT) and also for the
recipient.  One really shouldn't have to work this basic stuff out using:
$ ./bin/bbcmd hobbitd_alert --test
!
We definitely need some more complex examples.  Maybe someone who has a
complex and varied hobbit-alerts.cfg can post some sanitized examples that
someone can commit to SVN?

Many thanks,

SebA