Add A Glossary

Attached is a v1 patch to add a Glossary to the appendix of our current
documentation.

I believe that our documentation needs a glossary for a few reasons:

1. It's hard to ask for help if you don't know the proper terminology of
the problem you're having.

2. Readers who are new to databases may not understand a few of the terms
that are used casually both in the documentation and in forums. This helps
to make our documentation a bit more useful as a teaching tool.

3. Readers whose primary language is not English may struggle to find the
correct search terms, and this glossary may help them grasp that a given
term has a usage in databases that is different from common English usage.

3b. If we are not able to find the resources to translate all of the
documentation into a given language, translating the glossary page would be
a good first step.

4. The glossary would be web-searchable, and draw viewers to the official
documentation.

5. adding link anchors to each term would make them cite-able, useful in
forum conversations.

A few notes about this patch:

1. It's obviously incomplete. There are more terms, a lot more, to add.

2. The individual definitions supplied are off-the-cuff, and should be
thoroughly reviewed.

3. The definitions as a whole should be reviewed by an actual tech writer
(one was initially involved but had to step back due to prior commitments),
and the definitions should be normalized in terms of voice, tone, audience,
etc.

4. My understanding of DocBook is not strong. The glossary vs glosslist tag
issue is a bit confusing to me, and I'm not sure if the glossary tag is
even appropriate for our needs.

5. I've made no effort at making each term an anchor, nor have I done any
CSS styling at all.

6. I'm not quite sure how to handle terms that have different definitions
in different contexts. Should that be two glossdefs following one
glossterm, or two separate def/term pairs?

Please review and share your thoughts.