Update README.md

[santosomar]

This pull request includes significant updates to the ai_research/README.md file to enhance the organization and comprehensiveness of AI security and training resources. The changes include updating links, adding new sections for live training, reading lists, and video courses, and removing outdated or redundant links.

Updates to AI security resources:

• Updated links to AI security tools and frameworks, including new resources such as the OWASP AI Security Testing Guidance and Cisco AI Security Website.

Enhancements to training resources:

• Added a new section for live training sessions with a link to upcoming cybersecurity and AI training in O'Reilly.
• Introduced a reading list section with recommended books on AI and cybersecurity, providing links to O'Reilly for each book.
• Added a video courses section, listing various practical courses available on O'Reilly, including topics like building cybersecurity labs, AI-enabled programming, and securing generative AI.

Overall, these changes aim to provide a more structured and resourceful guide for users interested in AI security and training.

Fixes #257