[release-branch.go1.10-security] doc: document Go 1.10.6

Change-Id: I3fe44887a84586d73be01df78a9cbb002c1fc9c5
Reviewed-on: https://team-review.git.corp.google.com/c/376467
Reviewed-by: Filippo Valsorda <valsorda@google.com>
diff --git a/doc/devel/release.html b/doc/devel/release.html
index b8a6caf..cb2af29 100644
--- a/doc/devel/release.html
+++ b/doc/devel/release.html
@@ -72,6 +72,13 @@
 1.10.5 milestone</a> on our issue tracker for details.
 </p>
 
+<p>
+go1.10.6 (released 2018/12/12) includes three security fixes to "go get" and
+the <code>crypto/x509</code> package.
+See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.10.6">Go
+1.10.6 milestone</a> on our issue tracker for details.
+</p>
+
 <h2 id="go1.9">go1.9 (released 2017/08/24)</h2>
 
 <p>