Add documentation/spec for format of JSON data that comes from the API.

[farmdawgnation]

The README.md file in the project root defines the initial ideas for what API endpoints we should have, but we should probably create some more detailed documentation.

I propose the creation of a doc folder at the top of the repository that will contain documentation for each type of record that someone can request from the API.

Such documentation would include:

• The name of the type of record (e.g. "candidate")
• The keys that will appear in that record, and what they will contain.

As far as I can tell there will be three types of records:

1. Candidates
2. Campaigns
3. Campaign Reports

A candidate may have one or more campaigns associated with it. A campaign will have one or more report associated with it. These relationships should be taken into account.

We should also plan to have this data be denormalized.