Create tutorial for the system.

There are a few important tutorials, which should be written as notebooks, let's do them in this order:

1. Construct pipeline (with code and with config, use existing processor as examples)
1. Write a reader
1. Write a pack processor
1. Understand ontology (using ontology generator)
1. Write a batch pack processor (batch processor and batcher)
1. Write a trainer
1. Build a training pipeline (preprocess, resources and executor)
1. Model reuse
1. Construct pipelines with Multipacks (multipack processor, selector)
1. Understand Information Retrieval pipeline

Start by reviewing the existing processor examples and the notebook approach, then trace the mentioned ontology generator, batch processor and batcher, preprocessing, resources and executor, multipack processor and selector. Done means adding notebooks that cover the tutorials in the listed order, including code and configuration examples where requested.

Written by the indexing model from the issue text.