[release-branch.go1.12] doc: fix typo in Go 1.12.14 document

Change-Id: I3641a086f167a1337aaaacd2d758b6a42b84a7fb
Reviewed-on: https://go-review.googlesource.com/c/go/+/209845
Run-TryBot: Carlos Amedee <carlos@golang.org>
Run-TryBot: Alexander Rakoczy <alex@golang.org>
Reviewed-by: Alexander Rakoczy <alex@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
(cherry picked from commit 98e7270a)
Reviewed-on: https://go-review.googlesource.com/c/go/+/209846

doc/devel/release.html

@@ -127,7 +127,7 @@ Only macOS users who hit this issue need to update.
 </p>
 
 <p>
-go1.12.14 (released 2019/12/4) includes a fix to the runtime. See
+go1.12.14 (released 2019/12/04) includes a fix to the runtime. See
 the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.12.14">Go
 1.12.14 milestone</a> on our issue tracker for details.
 </p>