Squash doc levels

[jo-mueller]

This pull request primarily involves cleanup and reorganization of documentation files in the project. Key changes include the removal of unused headers, the reorganization of example workflows, and updates to image paths in a tutorial file.

Documentation Cleanup:

• Removed unused headers and topics from the Readme.md files in the docs/01_code_usage/01_toolboxes, docs/01_code_usage/02_example_workflows, docs/02_interactive_usage/01_toolboxes, and docs/02_interactive_usage/02_example_workflows directories. [1] [2] [3] [4]

Documentation Reorganization:

• Renamed the file docs/02_interactive_usage/02_example_workflows/demo_fit_ellipsoid_interactive.md to docs/02_interactive_usage/demo_fit_ellipsoid_interactive.md for better organization.

Tutorial Updates:

• Updated image paths in the demo_fit_ellipsoid_interactive.md tutorial to reflect the new directory structure.