Improve the README

[StevenWInfo]

There's a list of things to add or improve about the current README.

• [x] Clean up what is currently there.
• [x] Give some examples of how to use it. Even small programs might be appropriate.
• [x] Make a basic introduction of how to use it.
• [x] Give some basic reference info like all of the SodaTypes and maybe SODA functions/operators.
• [x] Maybe explain some of the design decisions made.
• [x] Give some of the concessions that the library makes, how it could possibly be improved, and mention issues and pull requests.
• [ ] Maybe installation and usage instructions?
• [x] Point toward other documentation like generated Haddock documentation.
• [x] Mention that it doesn't include any SODA publishing functionality and that it will hopefully be added in the future.
• [x] Other important things about using the library that people might need to know: Inconsistencies, tips, neat features, etc.

[StevenWInfo]

I didn't put installation instructions, but otherwise I did everything else. I might put in installation instructions later, but I think I'll close this bug for now.