doc: add Code of Conduct

Fixes #13073

Change-Id: I4fd9c6c61f1b9d49f66816839ca35209b4147ae3
Reviewed-on: https://go-review.googlesource.com/17167
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/doc/help.html b/doc/help.html
index 2cc4780..979d7bc 100644
--- a/doc/help.html
+++ b/doc/help.html
@@ -48,3 +48,9 @@
 meet to talk about Go. Find a chapter near you.
 </p>
 
+<h3 id="conduct"><a href="/conduct">Code of Conduct</a></h3>
+<p>
+Guidelines for participating in Go community spaces
+and a reporting process for handling issues.
+</p>
+