Update repository metadata

[jasonmccallister]

To increase discoverability, we should add the following to this repo under the about:

1. Add a description (if not already there) mentioning @dagger
2. In the website section, add a link to our docs page docs.dagger.io/features/llm
3. Topics: Add relevant topics, but keep to under 10.

Recommended topics:

• ai-agent
• typescript
• cypress
• testing