docs: Document VLM support requirement in extraction example (#2231)

* docs: Document VLM support requirement in extraction example

* DCO Remediation Commit for Tamás Bitai <bitai.tamas@gmail.com>

I, Tamás Bitai <bitai.tamas@gmail.com>, hereby add my Signed-off-by to this commit: b90defdb77

Signed-off-by: Tamás Bitai <bitai.tamas@gmail.com>

---------

Signed-off-by: Tamás Bitai <bitai.tamas@gmail.com>

docs/examples/extraction.ipynb

@@ -29,6 +29,16 @@
     "Check out the subsections below for different usage scenarios."
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "f52005fe",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "%pip install -q docling[vlm]  # Install the Docling package with VLM support"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 1,