[docbook-tc] Annotation element: Some rendered examples

While the contents of an Annotation element need not actually be
rendered as pop-up text, I thought it might be useful to provide some
examples of what "rich" annotative pop-up text might look like.

Here's an example that shows rendering of a couple of annotations in
HTML/Javascript:

  http://www.logopoeia.com/docbook/dontlearn.html#les2

If you mouse over the phrase "because I just happen to have such a
table handy" on that page, you will get a pop-up annotation that
includes an embedded image and a hyperlink. If you mouse over the
"Table 1." part of the table title, you'll see a second annotation.

As far as I can tell, annotations (or "notes", as Adobe now calls
them) in PDFs are limited to unformatted plain text, with no embedded
images or hyperlinks. Nevertheless, I thought it might be useful to
also show examples of what annotations looks like in a PDF file:

  http://www.logopoeia.com/docbook/dontlearn.pdf

You can view the annotations in that by double-clicking on the phrase
"I just happen to have such a table" and on the annotation/note marker
to the right of the table.

  --Mike