docs: add link to the blogpost in app

app.py

@@ -74,6 +74,7 @@ app = gr.Interface(
     outputs=[
         gr.Gallery(label="Retrieved Images"),
     ],
+    article="## To read more about the development of the app please refer to the [Lightly AI blogpost on Vector Indexes and Image Retrieval](http://www.lightly.ai/post/vector-indexes-and-image-retrieval-using-lightly)",
 )
 
 if __name__ == "__main__":