[release-branch.go1.9] doc: document Go 1.9.4

Change-Id: Ia3e35328d50bbd08948b34e09a9e8bb4f9b07888
Reviewed-on: https://team-review.git.corp.google.com/213170
Reviewed-by: Andrew Bonventre <andybons@google.com>
diff --git a/doc/devel/release.html b/doc/devel/release.html
index 24fe583..d82fb0c 100644
--- a/doc/devel/release.html
+++ b/doc/devel/release.html
@@ -57,6 +57,12 @@
 1.9.3 milestone</a> on our issue tracker for details.
 </p>
 
+<p>
+go1.9.4 (released 2018/02/07) includes a security fix to “go get”.
+See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.9.4">Go
+1.9.4</a> milestone on our issue tracker for details.
+</p>
+
 <h2 id="go1.8">go1.8 (released 2017/02/16)</h2>
 
 <p>
@@ -114,6 +120,13 @@
 1.8.6 milestone</a> on our issue tracker for details.
 </p>
 
+<p>
+go1.8.7 (released 2018/02/07) includes a security fix to “go get”.
+It contains the same fix as Go 1.9.4 and was released at the same time.
+See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.8.7">Go
+1.8.7</a> milestone on our issue tracker for details.
+</p>
+
 <h2 id="go1.7">go1.7 (released 2016/08/15)</h2>
 
 <p>