add note to all promptfoo lectures

prompt_evaluations/09_custom_model_graded_prompt_foo/lesson.ipynb

@@ -5,6 +5,10 @@
    "metadata": {},
    "source": [
     "# Custom model-graded evals \n",
+    "\n",
+    "**Note: This lesson lives in a folder that contains relevant code files. Download the entire folder if you want to follow along and run the evaluation yourself**\n",
+    "\n",
+    "\n",
     "In this lesson, we'll see how we can write custom model-graded evaluations using promptfoo. We'll start with a simple prompting goal: we want to write a prompt that can turn long, technically complex Wikipedia articles into short summaries appropriate for a grade school audience.\n",
     "\n",
     "For example, given the entire [Wikipedia entry on convolutional neural networks](https://en.wikipedia.org/wiki/Convolutional_neural_network), we want simple output summary like this one:\n",