[docs]: add subgraph streaming how-to (and some small cleanups) (#1606)

* wip

* spelling

* edit format_namespace

examples/streaming-from-final-node.ipynb

@@ -13,7 +13,11 @@
    "id": "964686a6-8fed-4360-84d2-958c48186008",
    "metadata": {},
    "source": [
-    "A common use case is streaming from an agent is to stream LLM tokens from inside the final node. This guide demonstrates how you can do this."
+    "A common use case is streaming from an agent is to stream LLM tokens from inside the final node. This guide demonstrates how you can do this.\n",
+    "\n",
+    "## Setup\n",
+    "\n",
+    "First let's install our required packages and set our environment variables."
    ]
   },
   {
@@ -34,7 +38,7 @@
    "metadata": {},
    "outputs": [
     {
-     "name": "stdin",
+     "name": "stdout",
      "output_type": "stream",
      "text": [
       "OPENAI_API_KEY:  ········\n"