talks: add to 2016/refactor.article a link to issue 18130

Change-Id: I14b9ada64e25c6ba0530fabbd24e8ff98c252979
Reviewed-on: https://go-review.googlesource.com/33724
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/2016/refactor.article b/2016/refactor.article
index 3639a7d..8cc34ca 100644
--- a/2016/refactor.article
+++ b/2016/refactor.article
@@ -696,3 +696,4 @@
 Thanks to the many people who helped us [[https://golang.org/issue/16339][think through the design questions]]
 that got us this far and led to the alias trial during Go 1.8 development.
 I look forward to the Go community helping us again when we revisit this problem for Go 1.9.
+If you’d like to contribute, please see [[https://golang.org/issue/18130][issue 18130]].