add 5.3.7.1 release notes (#1038)

* add 5.3.7.1 release notes

docs/index.html

@@ -135,7 +135,7 @@ h3 {border-bottom: none;}
 
 <ul>
 <li><a href="legacy/pdf/release-notes/avereos_6.0_release_notes_600.pdf" target="_blank">Avere OS 6.0.0 Release Notes (PDF)</a></li>
-<li><a href="legacy/pdf/release-notes/avereos_5.3_release_notes_5365.pdf" target="_blank">Avere OS 5.3 Release Notes (PDF)</a> - currently at version 5.3.6.5
+<li><a href="legacy/pdf/release-notes/avereos_5.3_release_notes_5371.pdf" target="_blank">Avere OS 5.3 Release Notes (PDF)</a> - currently at version 5.3.7.1
   <ul>
    <li>Previous 5.3 release information: <a href="legacy/pdf/release-notes/avereos_5.3_release_notes_5342.pdf" target="_blank">version 5.3.4.2</a></li>
   </ul>