Change example server port to 8080 and include Docker Compose example

docker-compose.yml

@@ -0,0 +1,14 @@
+version: '3'
+
+services:
+  map:
+    image: overv/openstreetmap-tile-server
+    volumes:
+      - openstreetmap-data:/var/lib/postgresql/12/main
+    ports:
+      - "8080:80"
+    command: "run"
+
+volumes:
+  openstreetmap-data:
+    external: true