Update nginx.conf

extend example nginx config to listen on IPv6 addresses as well as IPv4.

contrib/nginx.conf

@@ -1,6 +1,7 @@
 server {
     listen 443 ssl;
-
+    listen [::]:443 ssl;
+    
     # CHANGE THIS TO YOUR SERVER'S NAME
     server_name netbox.example.com;
 
@@ -24,6 +25,7 @@ server {
 server {
     # Redirect HTTP traffic to HTTPS
     listen 80;
+    listen [::]:80;
     server_name _;
     return 301 https://$host$request_uri;
 }