Bug 1610120 - Mention that NPAPI plugin support other than Flash was removed for 2.53.1. r=fg

src/releases/seamonkey2.53.1/index.en.html

@@ -97,6 +97,9 @@ for new information.
   </li>
   <li>TLS 1.3 is the default version now.
   </li>
+  <li>The only NPAPI plugin which will work with [% rnote.basename %] is Flash.
+    Support for other NPAPI plugins like Java and Silverlight has been removed.
+  </li>
 </ul>
 
 <p>