Feedback for “Build an AI Discord Bot with Rust and Rig: Step-by-Step Guide”

This tutorial probably needs updating. I was not able to find rig::rag::RagAgent and then I see in the [CHANGELOG](https://github.com/0xPlaygrounds/rig/blob/6f12c974b2eac7d7bb1f7ac94445bd6e726d737b/rig-core/CHANGELOG.md?plain=1#L226) that it has been deprecated:

- Deprecate RagAgent and Model in favor of versatile Agent

I am not sure how to make the adjustment from RagAgent to versatile Agent.

There are also a few other items I had to change. I had to add these two imports:

use rig::vector_store::in_memory_store::InMemoryVectorIndex;
use rig::vector_store::VectorStore;

And I was not able to get the \`\`\` to compile so I have to wrap the string with r#...#.

I was not able to complete the tutorial because of the RagAgent issue, so I look forward to an update soon.