app: add instructions for content removal

Fixes golang/go#18530.

Change-Id: I1b0f4d29b121c33551a6b3aab59a39a54c05974a
Reviewed-on: https://go-review.googlesource.com/34912
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/app/goplay/edit.html b/app/goplay/edit.html
index 6dc0909..740e98d 100644
--- a/app/goplay/edit.html
+++ b/app/goplay/edit.html
@@ -159,10 +159,17 @@
 The playground service is used by more than just the official Go project
 (<a href="//gobyexample.com/">Go by Example</a> is one other instance)
 and we are happy for you to use it on your own site.
-All we ask is that you <a href="mailto:golang-dev@googlegroups.com">contact us first</a>,
+All we ask is that you
+<a href="mailto:golang-dev@googlegroups.com">contact us first (note this is a public mailing list)</a>,
 use a unique user agent in your requests (so we can identify you),
 and that your service is of benefit to the Go community.
 </p>
+
+<p>
+Any requests for content removal should be directed to
+<a href="mailto:security@golang.org">security@golang.org</a>.
+Please include the URL and the reason for the request.
+</p>
 		</div>
 	</body>
 </html>