Cleaning up nginx conf

folder - `nginx/conf`
we need to clean it up keeping v4 structure in mind.

- [ ] cleanup *global* nginx.conf at `nginx/conf/ nginx.conf`in the repo. `/usr/local/openresty/nginx/conf/nginx.conf` inside container
- [ ] nginx.conf will include site specific config from `/var/www/conf/nginx/site.conf`. EEv4 will create/generate this file.

Users can create additional conf files in `/var/www/conf/nginx/custom/` with `.conf` extension. Something like `/var/www/conf/nginx/custom/redirects.conf`.

https://blog.martinfjordvald.com/2013/04/nginx-config-history-fastcgi_params-versus-fastcgi-conf/