Bug 26314: (QA follow-up) Improve POD and fix links for UseControlNumber off

Bug 26314: (QA follow-up) Improve POD and fix links for UseControlNumber off

When UseControlNumber is off, we previously did a search on the title index,
but this was not actually correct. It might work when we have a dependent
title and the title also appears on 245$p, but there is a better way:

The title of the set record will be found in:
* 773$3 for a dependent title
* 800/810/811/830 for an independent title

The search indices to use are host-item and title-series.

As we are not only looking for 773, POD was adjusted to reflect that.

Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>