doc/go1.8: remove mention of #16396

Change-Id: I811e76c9f42505e974bea634d4ded2499e4893db
Reviewed-on: https://go-review.googlesource.com/33926Reviewed-by: Ian Lance Taylor <iant@golang.org>

doc/go1.8.html

@@ -116,8 +116,7 @@ and cancelation.
 There are some instabilities on FreeBSD and NetBSD that are known but not understood.
 These can lead to program crashes in rare cases.
 See
-<a href="https://golang.org/issue/15658">issue 15658</a>,
-<a href="https://golang.org/issue/16396">issue 16396</a>, and
+<a href="https://golang.org/issue/15658">issue 15658</a> and
 <a href="https://golang.org/issue/16511">issue 16511</a>.
 Any help in solving these issues would be appreciated.
 </p>