Problem: Not enough information when reaching acmetool ratelimit.

[mamedin]

This is not a real role issue, but some information can be added to the README.md file to manage the acmetool ratelimit issue.

[mamedin]

Let’s Encrypt provides rate limits to ensure fair usage by as many people as possible:

https://letsencrypt.org/docs/rate-limits/

I have found problems with new certificate requests for the sfu.ca domain. The main limit is Certificates per Registered Domain was reached (20 per week).

I investigated about this issue, and I found very useful the lectl tool. This tool shows the exact time when you can request a new certificate:

./lectl -seul -m2000 sfu.ca
lectl 0.15 (2018-April-16)

2018/July/03 12:56:09 - Checking all certs for sfu.ca

I have found 1084 certificates (827 final certs and 257 pre certs) (max number of certs searched: 2000) for domain sfu.ca and its subdomains *.sfu.ca

CRT ID     CERT TYPE   DOMAIN (CN)                       VALID FROM             VALID TO               EXPIRES IN  SANs
572369489  Pre cert    labhazindex-dev.its.sfu.ca        2018-Jul-03 08:42 UTC  2018-Oct-01 08:42 UTC  89 days     labhazindex-dev.its.sfu.ca
...
...
...
12567287   Final cert  sentinel.iat.sfu.ca               2016-Feb-04 03:32 CET   2016-May-04 04:32 CEST  -790 days
12182674   Final cert  poeme.iat.sfu.ca                  2016-Jan-22 19:59 CET   2016-Apr-21 20:59 CEST  -802 days

Sorry, you can't issue any certificate, you already issued 20 certificates on last 7 days
You could issue next certificate on Thursday 2018-Jul-05 09:25:00 CEST

Note 1: Keep in mind that if sfu.ca is included in PSL (Public Suffix List) the rate limit could only be applied to your subdomain instead of your domain.
Note 2: Right now Let's Encrypt is implementing a new feature so if you renew the exact cert (with the same FQDNs) the rate limit could not apply to your domain if you try to renew it.

I think can add a brief review about this tool in the README file, in this way we can avoid blind tests to install a new certificate.