[OPEN-ILS-DOCUMENTATION] Documenting Use Cases in the official docs

[Jane Sandberg]

Hi all,

At yesterday's Hackfest, we decided to use the asciidoc sidebar
feature to draw attention to the use cases for individual features,
i.e. *why* somebody would want to use such a feature.

Here's an example of what they look like:
http://docs.evergreen-ils.org/reorg/3.1/command_line_admin/_aging_circulations.html

And here's some more info from our style guide:
https://wiki.evergreen-ils.org/doku.php?id=evergreen-docs:dig_style_guide#use_case

Let me know if you have any questions!

-Jane