Document example of adding your own classifier

[wmwv]

Provide example with documentation that steps a new person through how to add a module.

The current README.md for this repo details how to start and run things. This issue is about detailing how to write the code.

Once we have MicroLIA and SuperNNova clearly separated out, that should provide some opportunities for thinking about how to add a template example. Maybe there even should be a "template" directory for a certainly common type of classifier (in terms of expected input and produced output).