Add link to Graph RAG-based notebook example (#579)

Author: Paul-Cornell

examplecode/notebooks.mdx

@@ -6,6 +6,13 @@ description: "Notebooks contain complete working sample code for end-to-end solu
 ---
 
 <CardGroup cols={2}>
+    <Card title="Building Graph-Based RAG Applications" href="https://colab.research.google.com/drive/1z-eJPqQEFoZKx7hgi6uq0cbkF44JszlZ?usp=sharing">
+    <br/>
+       Learn how to use the Unstructured API to create a Graph RAG-based workflow that writes data with named entity recognition (NER) to your Astra DB.
+    <br/>
+       ``Unstructured API`` ``Workflows`` ``Graph RAG`` ``NER`` ``Astra DB``
+    <br/>
+    </Card>
     <Card title="Getting Started with Unstructured API and Delta Tables in Databricks" href="https://colab.research.google.com/drive/1ujLZoLx0ai0GAjvr9Xmze4UReZjKa8cU?usp=sharing">
     <br/>
        Learn how to create data processing workflows with Unstructured API and its Python SDK to preprocess all of your unstructured data into your Delta Table.