design/25530-notary: add link to ACM Queue CT article

Change-Id: I0d773d49b92184317817c426d268b59acafdba48
Reviewed-on: https://go-review.googlesource.com/c/proposal/+/165019
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/design/25530-notary.md b/design/25530-notary.md
index a066921..9fcbba7 100644
--- a/design/25530-notary.md
+++ b/design/25530-notary.md
@@ -148,6 +148,10 @@
 
 For details about the data structure, see Russ Cox’s blog post,
 “[Transparent Logs for Skeptical Clients](https://research.swtch.com/tlog).”
+For a high-level overview of Certificate Transparency
+along with additional motivation and context,
+see Ben Laurie's ACM Queue article,
+“[Certificate Transparency: Public, verifiable, append-only logs](https://queue.acm.org/detail.cfm?id=2668154).”
 
 The use of a transparent log for module hashes aligns with
 a broader trend of using transparent logs to enable detection