Here is a simple way to enable directory listing in Nginx Webserver.
I have a subdomain repository.wowtutorial.org and i want repository.wowtutorial.org to have ability to listing a directory.

All we need to do just modify the vhosts or nginx.conf
Add autoindex on;

Please see the example below

Example :

#pico /usr/local/etc/nginx/vhosts/repository.wowtutorial.org