update user guide / website

Some changes to the source code have not yet been updated in the User Guide:

• Check all code snippets (if they still correspond to the current code, for example args in plotters)
• Replace plots with the version using aixd-colors (after !163 (merged) merged) - in chapters: Getting started, ML model, Plotter
• Update "# Error during generation" snippet block in ML model section
• Warning block in Plotter about datablocks