Merge in files from docker repository.

This will allow easier building on docker hub and let us automatically
publish tags for each release.

Fixes oragono/oragono-docker#20

distrib/docker/docker-compose.yml

@@ -0,0 +1,20 @@
+version: "3.2"
+
+services:
+  oragono:
+    image: oragono/oragono:latest
+    ports:
+      - "6667:6667/tcp"
+      - "6697:6697/tcp"
+    volumes:
+      - data:/ircd
+    deploy:
+      placement:
+        constraints:
+          - "node.role == manager"
+      restart_policy:
+        condition: on-failure
+      replicas: 1
+
+volumes:
+  data: