Add Debug.Notes field to metadata and debug view

[nealey]

Summary

We need a new Notes field to house the instructor manual(s).

Motivation

The Cyber Fire sponsor at one point asked us to begin work on a TA manual. This has evolved into "make really good in-system notes for puzzles", at least for Netarch.

Describe alternatives you've considered

We examined a traditional manual and a slide presentation, but, for Netarch at least, decided that in-game notes would be far more helpful.

This will require some additional work on the user interface as well, since this section will be pretty big (and probably formatted with Markdown).