Added link to the Colab notebook of the Llama Stack lesson on the Llama 3.2 course on DLAI (#445)

# What does this PR do?

It shows a complete zero-setup Colab using the Llama Stack server
implemented and powered by together.ai: using Llama Stack Client API to
run inference, agent and 3.2 models. Good for a quick start guide.



- [ ] Addresses issue (#issue)


## Test Plan

Please describe:
 - tests you ran to verify your changes with result summaries.
 - provide instructions so it can be reproduced.


## Sources

Please link relevant resources if necessary.


## Before submitting

- [ ] This PR fixes a typo or improves the docs (you can dismiss the
other checks if that's the case).
- [ ] Ran pre-commit to handle lint / formatting issues.
- [ ] Read the [contributor
guideline](https://github.com/meta-llama/llama-stack/blob/main/CONTRIBUTING.md),
      Pull Request section?
- [ ] Updated relevant documentation.
- [ ] Wrote necessary unit or integration tests.

docs/zero_to_hero_guide/Tool_Calling101_Using_Together's_Llama_Stack_Server.ipynb

@@ -132,15 +132,6 @@
         "    return Agent(client, agent_config)"
       ]
     },
-    {
-      "cell_type": "markdown",
-      "metadata": {
-        "id": "iMVYso6_xoDV"
-      },
-      "source": [
-        "Quickly and easily get a free Together.ai API key [here](https://api.together.ai) and replace \"YOUR_TOGETHER_API_KEY\" below with it."
-      ]
-    },
     {
       "cell_type": "code",
       "execution_count": null,