Add Sphinx documentation. Note the code lives in docs and it produces the following webpage: https://fair4hep.github.io/hbb_interaction_network/

This can be separate pages or adding doc strings to existing scripts I think (to be understood).

At a minimum, I would add a few pages:

• getting started: create a page with commands on how to process data, train, predict (with and/or without GPU?) inside of provided docker container @billy000400
• dataset: document the dataset features used; copying liberally from http://opendata.cern.ch/record/12102 @jmduarte
• training: document all options of training script @yorkiva
• prediction: document all options of prediction script @poem2018

Extras:

• explainable: document options of explainable AI script? @yorkiva

@poem2018 I believe you created a singularity image for running the model. Could this be added to the repo?