Create documentation and example notebooks for various new features

[jvshields]

Many features exist in stardis at this point which are just found in the config schema. We should make notebooks that detail the various things you can do, like add molecules to the simulation, add various sources of continuum opacity, use spherical geometry, parallelize simulations, etc.

[jvshields]

One notebook should go through and detail the model, plasma, and radiation_field objects, that you can ask the simulation to return them in the config schema, the information that they contain, and some interesting things you can do with them.