README - this -> the `copy-sample-config.sh` script

Signed-off-by: Pang Yan Han <yanhan@viki.com>
README - state that defaults have been set for `cluster.xml`

Signed-off-by: Pang Yan Han <yanhan@viki.com>
README - add note on Storm components to run on each machine

Signed-off-by: Pang Yan Han <yanhan@viki.com>
README - say that `./start-storm.sh all` is for one machine setups

Signed-off-by: Pang Yan Han <yanhan@viki.com>
README - remove redundant words

Signed-off-by: Pang Yan Han <yanhan@viki.com>