Update README.md

Fix #323.

README.md

@@ -52,7 +52,9 @@ Example Caddyfile (replace `user` and `pass` accordingly):
     hide_via
     probe_resistance
   }
-  file_server { root /var/www/html }
+  file_server {
+    root /var/www/html
+  }
 }
 ```
 `:443` must appear first for this Caddyfile to work. For more advanced usage consider using [JSON for Caddy 2's config](https://caddyserver.com/docs/json/).