Add ipv6 in nginx config

[alan7000]

Is your feature request related to a problem? Please describe.
My current problem is that my docker server is ipv6 only. The problem is that the nginx server used in the image only listens in ipv4.

Describe the solution you'd like
Just add to the nginx configuration the fact that it also listens in ipv6.

Example:

listen [::]:8000;