design/cryptography-principles: add link to issue

Change-Id: I138ed5a82ad39d430435dc4d1ca5a44fc42ebf3a
Reviewed-on: https://go-review.googlesource.com/c/proposal/+/183920
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/design/cryptography-principles.md b/design/cryptography-principles.md
index a8fae63..4e97b18 100644
--- a/design/cryptography-principles.md
+++ b/design/cryptography-principles.md
@@ -1,8 +1,8 @@
 # Cryptography Principles
 
-Author: Filippo Valsorda
-
-Last updated: June 2019
+Author: Filippo Valsorda\
+Last updated: June 2019\
+Discussion: [golang.org/issue/32466](https://golang.org/issue/32466)
 
 https://golang.org/design/cryptography-principles