Add additional security topics to the book

[wmeints]

I left out some important security measures in the book. Some topics in the book cover essential security measures, but they could be a lot clearer. The plan is to add additional security content throughout the chapters in the upcoming weeks after I finish chapter 9.

The following list of topics need to be covered in addition to the existing content:

• How to mitigate prompt injection in RAG systems
• How to mitigate privilege escalation in tool calling and how to make tool calling secure in general

Note that I already have some pieces in place, which I'd like to highlight in case people get worried ;-)

• Prompt injection mitigation is covered and points toward jailbreak filters, etc.
• We covered monitoring of LLM-based applications
• The book explains how to handle PII filtering and when this becomes important
• The book also covers how to prevent XSS attacks and other dangerous code generation output