add nginx.conf and improve readme

dashy/docker-compose.yml

@@ -8,7 +8,7 @@ services:
     volumes:
       - ./config.yml:/app/public/conf.yml
     ports:
-      - 80:80
+      - 8000:80
     environment:
       - NODE_ENV=production
       - UID=1000

dashy/nginx.conf

@@ -0,0 +1,8 @@
+server {
+    server_name sudomain.your.domain;
+    location / {
+        proxy_pass http://127.0.0.1:8000;
+    }
+
+    listen 80; 
+}