missing information in add certificate in ACM

[xsalefter]

At the time of writing this issue, setup CNAME section in this docs need more explanation.

[1] .... The two strings labeled Name and Value should be copied to the two required entries for your CNAME. Copy these long strings carefully. Do not include any trailing periods. ....

Not all DNS manager in domain registrar should copy all those strings in ACM's CNAME name column. GoDaddy and Google Domains only need a prefix. See this so post.

[2] Your second CNAME is simpler. The Name entry will be kaui. The Value entry is the DNS name of your Load Balancer.

We need to add one or two paragraphs about the purpose of this. Maybe explain explicitly that we need 2 CNAME in our DNS Manager:

1. For ACM validation
2. For KAUI
3. For Kill Bill API it self, if needed (For discussion: I'm little bit confused as well about where we should put this information. Java Client for example, need extra work -- set certificate etc. if certificate is not valid or it is just self-signed certificate).