cleanup mentioned repos

[TimmRuppert]

Reference to a related issue in the repository

#84

Add a description

• Removed osi validation
• Restructured the overview into sections
• Added osi-cpp and osi-python
• Added all except the documentation repos to the menu bar dropdown (the thing in the top right)
• Removed old comments

Check the checklist

• I have performed a self-review of my own code/documentation.
• My documentation changes are related to another repository in the organization. Here is the link to the issue/repo.
• My changes generate no new warnings during the documentation generation.
• The Antora pipeline which pushes the documentation to gh-pages on the downstream repository passes with my changes.

[pmai]

CCB 2025-11-13: Merge as-is.