Production-Setup: document -ip.bind.localhost opt-out for the companion localhost listener

Production-Setup.md

@@ -32,6 +32,10 @@ ensure SeaweedFS uses the correct IP for cluster communication. Append
 If you wish to use a different IP address for user-facing services, then 
 set `-ip.bind=yy.yy.yy.yy` as well.
 
+Each service also listens on the same ports on `localhost`, so local
+tools can still reach it. To disable the extra localhost listener, add
+`-ip.bind.localhost=false`.
+
 ### For single node setup
 
 You can just use `weed server -filer -s3 -ip=xx.xx.xx.xx`, to have one master,