Use multiple sources in the COPY instruction

[refs #92a4265fce5f]

Author: jfahrer

nginx/Dockerfile

@@ -5,7 +5,7 @@ RUN apt-get install -y nginx
 RUN rm /var/log/nginx/access.log && ln -s /dev/stdout /var/log/nginx/access.log
 RUN rm /var/log/nginx/error.log && ln -s /dev/stderr /var/log/nginx/error.log
 
-COPY ./html/*.html /var/www/html/
+COPY ./html/*.html ./html/assets/ ./html/css/ /var/www/html/
 
 CMD ["/usr/sbin/nginx", "-g", "daemon off;"]