add restart for container autostart

Docker.md

@@ -35,6 +35,7 @@ services:
     image: rssbridge/rss-bridge:latest
     ports:
       - 3000:80
+    restart: unless-stopped
 ```
 
 You can save this file as `docker-compose.yml`, create a `whitelist.txt` file next to it (just leave the file empty) before running it using `docker-compose up`. Once it gets running, you can edit the `whitelist.txt` [as per the plugins you want to run](Whitelisting).