test: try again with certificate creation using letsencrypt in pulumi

knowledge base/letsencrypt.md

@@ -2,11 +2,15 @@
 
 1. [Challenges](#challenges)
    1. [DNS-01 challenge](#dns-01-challenge)
+1. [Limits](#limits)
+   1. [Duplicate certificates](#duplicate-certificates)
 1. [Further readings](#further-readings)
    1. [Sources](#sources)
 
 ## Challenges
 
+Refer [Challenge types].
+
 ### DNS-01 challenge
 
 Requires one to prove one has control over the DNS for one's domain name.<br/>
@@ -31,6 +35,29 @@ One can have multiple TXT records in place for the same name.<br/>
 However, make sure to clean up old TXT records: Let's Encrypt will start rejecting the request if the response size from
 the DNS gets too big.
 
+## Limits
+
+### Duplicate certificates
+
+Refer [Duplicate certificate limit].
+
+One can request a certificate issuance for **the same _exact set_ of hostnames** up to 5 times per week.<br/>
+Once that limit is exceeded, one should receive an error message like the following:
+
+```plaintext
+too many certificates (5) already issued for this exact set of domains in the
+last 168 hours: example.com login.example.com: see https://letsencrypt.org/docs/duplicate-certificate-limit
+```
+
+In this error message example, the _exact set_ is `["example.com", "login.example.com"]`.
+
+Revoking previously issued certificates will **not** reset the duplicate certificate limit.<br/>
+Nor that limit can be overridden at the time of writing.
+
+As a workaround, one can request one or more certificates for a **different** _exact set_ of hostnames.<br/>
+E.G., requesting a certificate for `[example.com, test.example.com]` will succeed; similarly, requesting separate
+certificates for the `[example.com]` and `[login.example.com]` sets will succeed.
+
 ## Further readings
 
 - [Website]
@@ -39,6 +66,7 @@ the DNS gets too big.
 ### Sources
 
 - [Challenge types]
+- [Duplicate certificate limit]
 
 <!--
   Reference
@@ -47,11 +75,12 @@ the DNS gets too big.
 
 <!-- In-article sections -->
 <!-- Knowledge base -->
-[acme]: acme.placeholder
+[acme]: acme.md
 
 <!-- Files -->
 <!-- Upstream -->
 [challenge types]: https://letsencrypt.org/docs/challenge-types/
+[duplicate certificate limit]: https://letsencrypt.org/docs/duplicate-certificate-limit/
 [website]: https://letsencrypt.org/
 
 <!-- Others -->