🐛 Fix frontend Dockerfile copying Nginx config

Author: tiangolo

{{cookiecutter.project_slug}}/frontend/Dockerfile

@@ -25,4 +25,4 @@ FROM nginx:1.15
 COPY --from=build-stage /app/dist/ /usr/share/nginx/html
 
 COPY --from=build-stage /nginx.conf /etc/nginx/conf.d/default.conf
-COPY ./nginx-backend.conf /etc/nginx/extra-conf.d/backend-not-found.conf
+COPY ./nginx-backend-not-found.conf /etc/nginx/extra-conf.d/backend-not-found.conf