[Suggestion] Add zeroSSL to free certificates

What would you like to be added or improved?

Currently the free SSL certificates are limited to Let's Encrypt.

Please add zeroSSL to the list of providers.

Why is it needed?

We would like to use OCSP stappling for the SSL-connection.
https://en.wikipedia.org/wiki/OCSP_stapling

Let's Encrypt stopped support for OCSP.

zeroSSL still supports OCSP so we want to use their certificates.