[Koha] Documentation Questions for 3.4

[Nicole Engard]

Hi all, I need some help documenting the following:

* OpacHiddenItems - I know it says to read the text file, but that
text file doesn't explain how this is to be used or why? What do I put
in the box? How do I format it? Why am I using this?
* UseControlNumber - What does this do? I'm totally clueless here.
* State fields for libraries and patrons - these will not populate
with states that were in the system already on upgrade - right?

Thanks in advance,
Nicole