Fix missing Jupyter reports

[JohT]

⚙️ Optimization

• Add logging for successful Jupyter conversions: Now, also successfully created files will be logged. This is helpful for troubleshooting to find out, which commands actually succeeded.

• Use the written out form for shell set options: The shell set commands for options are now written out instead of the one letter alternatives to enhance readability (a bit).

🛠 Fixes

• Fix figure title that shows spread and not usage
• Fix minor markdown linter warnings
• Use return instead of exit for sourced sub scripts: This fixes the missing Jupyter notebook output files because "exit" not only ended the sub script but also the main script that converts Jupyter notebooks to other file formats.