Warn the user if a DNS ACME challenge is required

[snowbldr]

I tried to set up automatic acme cert singing for a wildcard domain.
The certificates never got issues and I could not figure out why. The only message in the log was:

error=acme: urn:ietf:params:acme:error:orderNotReady: Order's status ("pending") is not acceptable for finalization

if an http01 challenge for a domain is not available, haproxy-ingress should print out the required information to complete the challenge and inform the user on how to proceed.

In the current state, it would not be possible to complete a dns01 challenge or set up a wildcard certificate using the acme support in haproxy-ingress.