NFC: Add link to the HOMOWP companion notebooks

[jsiirola]

Fixes # .

Summary/Motivation:

This adds a link to the companion notebooks for the textbook Hands-on Mathematical Optimization with Python (Postek, Zocca, Gromicho, and Kantor) to the list of examples and tutorials. The notebooks include links to directly run / explore them on Google Collab.

Changes proposed in this PR:

• Add link to HOMOWP companion notebooks

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