doc: correct link in 1.12.3 notes

Change-Id: I6dd60ea7b8a8756be97503e163c2386af16e4e12
Reviewed-on: https://go-review.googlesource.com/c/go/+/171144Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

doc/devel/release.html

@@ -51,7 +51,7 @@ command, the runtime, and the <code>doc</code>, <code>net</code>,
 <p>
 go1.12.3 (released 2019/04/08) fixes an issue where using the prebuilt binary
 releases on older versions of GNU/Linux
-<a href="https://golang/go/issues/31293">led to failures</a>
+<a href="https://golang.org/issues/31293">led to failures</a>
 when linking programs that used cgo.
 Only Linux users who hit this issue need to update.
 </p>