Add setup script to readme

[Deco354]

What

Adds a setup script that performs all necessary setup for the project
Adds a troubleshooting section to readme.

Why

Make it easier for people unfamiliar with this project, virtual environments or AI Safety research to set the project up. (We used this project as part of an AISafety course).

Testing

• Modify setup script to use circuit-tracer2 if your current environment is named circuit-tracer
• Run setup script within a directory that doesn't currently contain a circuit-tracer directory.
• Switch VSCode's notebook environment to your new env.
• Run `circuit-tracing-tutorial.ipynb