ZODB database packing configuration

[fulv]

Just leaving myself a todo here, unless someone else grabs it first.

In http://docs.plone.org/4/en/develop/plone/persistency/database.html#packing-through-the-web, this sentence packs a lot of jargon that needs explaining:

Manual packing can be executed through Zope Control Panel (not Plone control panel) in Zope application server root (not Plone site root) in ZMI.

• Zope Control Panel vs Plone control panel
• Zope application server root in ZMI vs Plone site root in ZMI

For a non-Plone insider, these are very obtuse statements. If these things are already defined in some kind of glossary somewhere else, then just linking to the definition would be stellar. Otherwise, we need to add those definitions.