Bug 6716 Document deleteditems table

Bug 6716 Document deleteditems table

This patch documents the deleted items table. Some fields were left
undocumented because I was unsure of what data was stored there:

stack - might be linked to shelving number, but need confirmation
paidfor - pretty sure this is unused, but don't want to document it that way

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
(cherry picked from commit c9441f48955360829ef7f8e97a54afa7aa31fc5b)

Signed-off-by: Chris Nighswonger <chris.nighswonger@gmail.com>