Broken link in free-programming-books-langs.md

The following book link is not working (shows a black page):

• Java 23 - Key Concepts in Brief - Sergio Petrucci (PDF)

Steps to reproduce

1. Open the link: https://petrucci.dev/java23.html
2. Page loads but content is missing / blank

Suggested workaround

I found a version in the Wayback Machine: Archived Java 23 PDF

Notes

• The current link should either be updated to a working version, or an access note added (e.g., archived).
• This is for the section in /books/free-programming-books-langs.md.