Add nginx HTTPS example config for subpath method

[le-roux]

The existing nginx config for the subpath method doesn't include the necessary elements to use HTTPS (contrary to the subdomain one). In addition to the new server entry, the proxy_pass value is updated to remove the /jellyfin/ suffix which creates an infinite redirect loop (as explained in https://www.reddit.com/r/jellyfin/comments/duhwjd/nginx_infinite_redirect_loop_after_upgrading_to/)

[Shadowghost]

The linter found some issues but that aside this should be fine. Didn't test it though.

[le-roux]

This config has been tested OK with :

• nginx version: nginx/1.18.0 (Ubuntu)
• Jellyfin.Server 10.8.1.0