Notebooks cleanup

[MarionBWeinzierl]

Closes #59 and closes #23

The following changes are made:

• Fix generate-paper-figure-1.ipynb and related code to generate figure 1
• Fix generate-figure-6.ipynb and related code to generate figure 6
• Fix test_global_control.ipynb and related code.
  - [ ] Fix further necessary notebooks - TODO: identify notebooks -> this has been moved to Fix and document remaining notebooks #93 in order to be able to merge the major changes from this PR
• Add descriptions and documentation about how to run the Jupyter notebooks, with what data, and what they generate
• Identify and remove no longer needed Jupyter notebooks

[MarionBWeinzierl]

@arthurBarthe , could you please identify which of these notebooks can be deleted, and which we should aim to get up and running again?

[MarionBWeinzierl]

@arthurBarthe , could you please identify which of these notebooks can be deleted, and which we should aim to get up and running again?

• multi-region* can be deleted
• shallow water/SWM to be discussed later
• experiments assorted can probably go
• Laure* can probably go