docker: rename docker-compose file.

Move the docker-compose file up to the root directory so you can just do
`docker-compose up` to bring up Danbooru.

docker-compose.yaml

@@ -0,0 +1,57 @@
+# A Docker Compose file that launches a minimal Danbooru instance. This is
+# suitable as a quick demo or for personal use, not for public-facing sites.
+#
+# This will start a Danbooru instance running on http://localhost.
+#
+# Usage:
+#
+#  docker-compose up
+#  docker-compose down
+#
+# References:
+#
+# * https://docs.docker.com/get-docker/
+# * https://docs.docker.com/compose/install/
+# * https://docs.docker.com/compose/compose-file/compose-versioning
+# * https://docs.docker.com/compose/release-notes
+
+# Version 3.4 is the latest version that is supported by the version of Docker
+# Compose shipped with Ubuntu 18.04 LTS (version 1.17.4).
+version: "3.4"
+
+services:
+  danbooru:
+    image: evazion/danbooru
+    # build:
+    #  context: ../..
+    #  dockerfile: config/docker/Dockerfile.danbooru
+    ports:
+      - "80:3000"
+    environment:
+      - RAILS_ENV=production
+      - RAILS_SERVE_STATIC_FILES=true
+      - DATABASE_URL=postgresql://danbooru@postgres/danbooru
+      - DANBOORU_CANONICAL_URL=http://localhost
+    volumes:
+      - "danbooru-images:/danbooru/public/data"
+    depends_on:
+      - postgres
+    command: ["bash", "-c", "bin/rails db:setup; bin/rails server -b 0.0.0.0"]
+    user: root
+
+  postgres:
+    image: evazion/postgres
+    # build:
+    #  context: .
+    #  dockerfile: Dockerfile.postgres
+    environment:
+      POSTGRES_USER: danbooru
+      POSTGRES_HOST_AUTH_METHOD: trust
+    volumes:
+      - "danbooru-data:/var/lib/postgresql/data"
+
+volumes:
+  danbooru-images:
+    name: danbooru-images
+  danbooru-data:
+    name: danbooru-data