feature request: custom error pages

[tonyengstrom]

Is it possible to import the default /etc/nginx/sites-enabled/default file into the container so one can add custom error pages as needed. The idea is that one would manually add custom error pages like 404.html into /usr/share/nginx/html and then add something like the below to /etc/nginx/sites-enabled/default file:

server {
        listen 80 default_server;
        listen [::]:80 default_server ipv6only=on;

        . . .

        **error_page 404 /custom_404.html;
        location = /custom_404.html {
                root /usr/share/nginx/html;
                internal;**
        }
}