Serve a local folder via the same server

To allow Mirador to access local files / manifests

Issue #2

.gitignore

+www/
 node_modules/
 dist/
 package-lock.json

docker-compose.yml

@@ -6,4 +6,5 @@ services:
     ports:
       - "8080:80"
     volumes:
+      - ./www:/srv/data
       - ./Caddyfile:/etc/caddy/Caddyfile