minor improvements or typos in readme

[Lovkush-A]

1. In this part, for each line, say which machine the command is run on.

- clone this repo on the proxy machine:
```git clone https://github.com/nickypro/arena-infra.git && cd arena-infra```
- copy the config.env file to the proxy machine:
```scp config.env myproxy:~/arena-infra/config.env```
- setup nginx on the proxy machine: `sudo bash ./proxy/setup_nginx.sh`.

2. Remove bracket. for the machines you have created).
3. Missing .py. python3 ./proxy/nginx_pods > ~/proxy.conf && systemctl restart nginx