Add documentation

[Goff-Davis]

Architecture Documentation

An ARCHITECTURE.md file should be created. See here for a somewhat preachy explanation of what that is.

It should cover:

• The flow of the mobile app, what pages there are, how are they connected
• Explain each component and where it fits in to the system. Special attention should be paid to major components, so a button doesn't need much explanation, but the home component has more going on.
• Anything else you think can help someone get an effective mental map of the mobile app.

Readme

Make sure the readme is up to date with all the latest environment variables, commands, and explanations on how to get started developing and deploying.

Commenting

Comments should be added to code that is complex or could be hard to understand. Don't do line by line or real nitty gritty stuff since that can change, but explain the reasoning behind a section, for example.