doc: document Go 1.8.5

Change-Id: I9241e6acb65c337b961eed9cdeaf4c041b6326a3
Reviewed-on: https://go-review.googlesource.com/73390
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>

doc/devel/release.html

@@ -78,6 +78,16 @@ See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.8.4">Go
 1.8.4 milestone</a> on our issue tracker for details.
 </p>
 
+<p>
+go1.8.5 (released 2017/10/25) includes fixes to the compiler, linker, runtime,
+documentation, <code>go</code> command,
+and the <code>crypto/x509</code> and <code>net/smtp</code> packages.
+It includes a fix to a bug introduced in Go 1.8.4 that broke <code>go</code> <code>get</code>
+of non-Git repositories under certain conditions.
+See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.8.5">Go
+1.8.5 milestone</a> on our issue tracker for details.
+</p>
+
 <h2 id="go1.7">go1.7 (released 2016/08/15)</h2>
 
 <p>