Improve website test score

[ddeboer]

https://internet.nl/site/termennetwerk.netwerkdigitaalerfgoed.nl/

Not reachable via modern internet address, or improvement possible (IPv6)

Unfortunately, DigitalOcean load balancers do not support IPv6.

Domain name not signed (DNSSEC)

Contacted DNS provider to add DNSSEC.
DigitalOcean does not support DNSSEC, so we may want to use Cloudflare instead.

Your web server offers an HSTS policy with a cache validity period (max-age) that is not sufficiently long (i.e. less than 1 year).

Fixed by upgrading nginx-ingress.

Added a .well-known/security.txt to all subdomains.