Tutorial.rst is too bulky and need clean up

Our tutorial documentation is too bulky: https://pypsa-earth.readthedocs.io/en/latest/tutorial.html Snakemake offers e.g. two tutorials. One that can be run in 10-20min another one that is extended and can take hours. In ours are too many explanations... making it difficult for new users to "taste" the model. Let's redesign our tutorial.

PyPSA-Eur does it great here with only three little sections:

Execute the tutorial config
Modify the workflow
Analyse the results

Suggestions

Let's create a 1:1 equivalent to PyPSA-Eur. (our current tutorial e.g. includes the cp config.default.yaml config.yaml --- This will lead bad user experience, use config.tutorial instead in all tutorials!)
Let's move the learning and prerequisite section material from tutorial.rst to learning_material.rst. There should be also the Developer videos https://pypsa-earth.readthedocs.io/en/latest/tutorial.html#youtube-devtutorials
Notebooks should be a separate .rst and not part of the tutorial.
Everything between Examples and Youtube-Dev can be deleted

pypsa-meets-earth / pypsa-earth

Tutorial.rst is too bulky and need clean up #496