docs: add feature description

README.md

@@ -6,6 +6,14 @@ It can be used with [kiliandeca/excalidraw-fork](https://gitlab.com/kiliandeca/e
 
 [DockerHub kiliandeca/excalidraw-storage-backend](https://hub.docker.com/r/kiliandeca/excalidraw-storage-backend)
 
+Feature:
+
+- Storing scenes: when you export as a link
+- Storing rooms: when you create a live collaboration
+- Storing images: when you export or do a live collaboration of a scene with images
+
+It use Keyv as a simple K/V store so you can use the database of your choice.
+
 ## Environement Variables
 
 | Name            | Description                                                  | Default value    |

docker-compose.yml

@@ -10,9 +10,12 @@ services:
     environment:
       BACKEND_V2_GET_URL: http://localhost:8080/api/v2/scenes/
       BACKEND_V2_POST_URL: http://localhost:8080/api/v2/scenes/
+      LIBRARY_URL: https://libraries.excalidraw.com
+      LIBRARY_BACKEND: https://us-central1-excalidraw-room-persistence.cloudfunctions.net/libraries
       SOCKET_SERVER_URL: http://localhost:5000/
       STORAGE_BACKEND: "http"
       HTTP_STORAGE_BACKEND_URL: "http://localhost:8080/api/v2"
+
   excalidraw-storage-backend:
     build: .
     ports: