Add Neon Postgres to the list of vector databases in the README (#746)

examples/vector_databases/README.md

@@ -17,6 +17,7 @@ Each provider has their own named directory, with a standard notebook to introdu
 - [Milvus](https://milvus.io/docs/example_code.md)
 - [MyScale](https://docs.myscale.com/en/quickstart/)
 - [MongoDB](https://www.mongodb.com/products/platform/atlas-vector-search)
+- [Neon Postgres](https://neon.tech/docs/ai/ai-intro)
 - [Pinecone](https://docs.pinecone.io/docs/quickstart)
 - [PolarDB](https://www.alibabacloud.com/help/en/polardb/latest/quick-start)
 - [Qdrant](https://qdrant.tech/documentation/quick-start/)