Improve Documentation for Building New Theories

[benbrastmckie]

I have begun to rework the theory_lib/README.md to better describe the basic architecture for each theory.
Here are some related TODOs (additions welcome) for adding docs to theory_lib/:

• Add DEVELOPMENT.md to document the steps to implementing a new theory
• Add licenses to existing theories, including details on how to add licenses to new theories
• Divide README.md into THEORY_ARCHITECTURE.md and README.md where the latter focuses on how to use existing theories

[benbrastmckie]

I just finished the THEORY_ARCHITECTURE.md document which provides a detailed description of theory contents.

[benbrastmckie]

I just finished revising theory_lib/README.md.