Add release notes.

(cherry picked from commit fce5a01a63)

doc/arm/notes-feature-changes.xml

@@ -0,0 +1,23 @@
+<!--
+ - Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ -
+ - This Source Code Form is subject to the terms of the Mozilla Public
+ - License, v. 2.0. If a copy of the MPL was not distributed with this
+ - file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ -
+ - See the COPYRIGHT file distributed with this work for additional
+ - information regarding copyright ownership.
+-->
+
+<section xml:id="relnotes_changes"><info><title>Feature Changes</title></info>
+  <itemizedlist>
+    <listitem>
+      <para>
+	NSEC Aggressive Cache (synth-from-dnssec) has been disabled by default
+	because it was found to have a significant performance impact on the
+	recursive service. The NSEC Aggressive Cache will be enable by default
+	in the future releases. [GL #1265]
+      </para>
+    </listitem>
+  </itemizedlist>
+</section>

doc/arm/notes.xml

@@ -25,6 +25,7 @@
   <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-download.xml"/>
   <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-sec-fixes.xml"/>
   <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-new-features.xml"/>
+  <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-feature-changes.xml"/>
   <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-bug-fixes.xml"/>
   <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-license.xml"/>
   <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="notes-eol.xml"/>

util/copyrights

@@ -1525,6 +1525,7 @@
 ./doc/arm/notes-bug-fixes.xml			SGML	2019
 ./doc/arm/notes-download.xml			SGML	2019
 ./doc/arm/notes-eol.xml				SGML	2019
+./doc/arm/notes-feature-changes.xml		SGML	2019
 ./doc/arm/notes-intro.xml			SGML	2019
 ./doc/arm/notes-license.xml			SGML	2019
 ./doc/arm/notes-new-features.xml		SGML	2019