Create Documentation and Tutorials

[hstrey]

@david-hofmann @SageanneS @anandpathak31 @ChrisRackauckas

We need to start working on the documentation for Neuroblox.jl. Even though we don't know when our package can be released, we should consider getting ready. And one important part of any software is its documentation. Here is a list of things that need to get done:

1. @ChrisRackauckas, would you mind setting up Documenter.jl in our runners so that the API is documented automatically? As far as I understand, because we are not open-source, we don't get free hosting for the documents, but we can always host it ourselves once we release it.

2. We need to add comment headers to all functions and struct definitions. Some of us have added them already.