Merge pull request #3 from tensorchord/readme

change README

README.md

@@ -1 +1,34 @@
-# cloudnative-vectorchord
+# cloudnative-vectorchord
+
+Container images for [cloudnative-pg](https://cloudnative-pg.io/) with the [VectorChord](https://github.com/tensorchord/VectorChord) extension installed.
+
+
+> [!IMPORTANT]
+> If you are using this image on an existing database, the postgres configuration needs to be 
+> altered to enable the extension. You can do this by setting shared_preload_libraries in your Cluster spec:
+> ```yaml
+> apiVersion: postgresql.cnpg.io/v1
+> kind: Cluster
+> spec:
+>   (...)
+>   postgresql:
+>     shared_preload_libraries:
+>       - "vchord.so"
+>   ```
+
+> [!IMPORTANT]
+> The `VectorChord` extension is not enabled by default. You need to enable it and set the search path when initializing the database. You can configure it in your Cluster spec:
+> ```yaml
+> apiVersion: postgresql.cnpg.io/v1
+> kind: Cluster
+> spec:
+>   (...)
+>   bootstrap:
+>     initdb:
+>       postInitSQL:
+>         - CREATE EXTENSION IF NOT EXISTS vchord CASCADE;
+
+## Building
+
+To build the Dockerfile locally, you need to pass the `CNPG_TAG` and `VECTORCHORD_TAG` args. For example:  
+`docker build . --build-arg="CNPG_TAG=16.3" --build-arg="VECTORCHORD_TAG_TAG=0.1.0"`