Create a Jupyter Notebook to explain simple access to the Character and Fix stores

[agstephens]

We need a front door to advertise the data stores and basic get and search access.

Note: these are for the public and production data stores.

A Notebook is a sensible approach.

Issues:

1. Where to put the Notebook?

• start by putting it in dachar/notebooks
• eventually, put all our project-level docs into a separate repo, or use ReadTheDocs

2. Content:

• Explain the workflow from character to fix.
• Include diagram
• Add sections:
  • Working with the Character Store
  • Working with the Fix Store

[agstephens]

Next step: mimic Carsten's rooki setup for using nbviewer and binder to run the Notebook in the cloud.