[O] Bulk function documentation is missing

[Bernt Hansen]

Hi Puneeth,

I just ran across the new Bulk action feature which applies a function
to the marked entries in the agenda.  There is no documentation for this
feature that I can find other than in the commit itself.

This functionality was added by you in 5b1b94a (* org-agenda.el
(org-agenda-bulk-action): Allow the user to run a function., 2011-03-08)

Could you please also provide documentation in org.texi with an example
of how you use this?

Thanks,
Bernt