design/56986-godebug: link to proposal

Change-Id: Ia89ab416b1b631a47bc76f186a6832f25b3ca2e7
Reviewed-on: https://go-review.googlesource.com/c/proposal/+/454018
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/design/56986-godebug.md b/design/56986-godebug.md
index bd6ed9e..c8b59ac 100644
--- a/design/56986-godebug.md
+++ b/design/56986-godebug.md
@@ -5,7 +5,7 @@
 
 Earlier discussion at https://go.dev/issue/55090.
 
-Proposal at https://golang.org/issue/NNNNN.
+Proposal at https://go.dev/issue/56986.
 
 ## Abstract