Move pthread rwlocks release note to a section

doc/arm/notes-9.17.0.xml

@@ -10,6 +10,10 @@
 -->
 
 <section xml:id="relnotes-9.17.0"><info><title>Notes for BIND 9.17.0</title></info>
+
+  <section xml:id="relnotes-9.17.0-changes"><info><title>Feature Changes</title></info>
+    <itemizedlist>
+      <listitem>
         <para>
           System-provided pthread rwlocks implementation is used by default instead of
           built-in ISC implementation of rwlocks. Please be aware that unpatched glibc
@@ -24,9 +28,7 @@
           xlink:href="https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1864864">fixed
           version</link>.
         </para>
-
-  <section xml:id="relnotes-9.17.0-changes"><info><title>Feature Changes</title></info>
-    <itemizedlist>
+      </listitem>
       <listitem>
         <para>
           The <command>rndc nta -dump</command> and