docs: tutorial should mention that Ollama must be running

[divilian]

Describe the bug
The intro tutorial requires that the user have Ollama installed and running on port 11434, but never mentions that fact. New users who want to give the tutorial a spin to see how mesa-llm works may be frustrated and disappointed.

[IlamaranMagesh]

This is true. We have not exposed the api_base to LLMAgent module as well. More about here, #172