DoH/DoT/DoQ https dns spoofing

### Prerequisites

- [X] I have checked the [Wiki](https://github.com/AdguardTeam/AdGuardHome/wiki) and [Discussions](https://github.com/AdguardTeam/AdGuardHome/discussions) and found no answer

- [X] I have searched other issues and found no duplicates

- [X] I want to request a feature or enhancement and not ask a question

### Description

#### What problem are you trying to solve?
My goal is to dns spoof blocked domains to a custom block page with https support. Only issue is that I need to generate a .crt certificate file if I want a custom block page for https. But how do I do this with certbot?

DNS providers like NextDNS have their own .crt certificate for https custom block page. And DNS providers like NextDNS use pihole/adguardhome for blocking ads.

So how do I generate my own .crt cert? (not .pem cert) I already have my certificates for https dashboard and tls/https/quic dns.

#### Proposed solution
You could make a guide on the wiki on how to do this.
Or link a guide that redirects to another website on how to do this.

#### Alternatives considered
None available

#### Additional information
None