update readme with example

README.md

@@ -1,2 +1,18 @@
 # Vintagestory Docker
 Docker images for Vintagestory.
+
+## Example
+An example using docker compose.
+
+```yaml
+services:
+  "vintagestory":
+    image: "git.1e99.eu/1e99/vintagestory:latest"
+    volumes:
+      - "./vintagestory:/data"
+    environment:
+      - "VS_VERSION=1.20.7"
+    ports:
+      - "42420:42420/tcp"
+      - "42420:42420/udp"
+```