chore: update nginx build instructions

Make compatible with newest nginx Dockerfile

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

docker-compose.yml

@@ -62,7 +62,9 @@ services:
       - host.docker.internal:host-gateway
   nginx:
     image: ghcr.io/librecodecoop/nextcloud-dev-nginx:latest
-    # build: .docker/nginx
+    # build:
+    #   context: .docker
+    #   dockerfile: Dockerfile.nginx
     restart: unless-stopped
     volumes:
       - ./volumes/nextcloud:/var/www/html:ro