Bug 1689878 - Update SeaMonkey website for 2.53.7 Beta release - addendum. r=IanN

src/releases/seamonkey2.53.7/index.en.html

@@ -93,7 +93,7 @@ for new information.
 <a href="../seamonkey[% rnote.relativeto.version %]/#new">[% rnote.relativeto.name %]</a>:
 </p>
 <ul>
-  <li>Remove Flash and NPAI support <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1688415">bug 1688415</a>.
+  <li>Remove Flash and NPAPI support <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1688415">bug 1688415</a>.
   </li>
   <li>Switch packaged extensions to be global <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1659298">bug 1659298</a>.
   </li>
@@ -101,10 +101,16 @@ for new information.
   </li>
   <li>Fix an issue with copying to IMAP sent folder and some reference count
     leaks in mailnews <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1689890">bug 1689890</a>.
-  <li>Domain tailing has been enabled.
+  <li>Tailing to delay tracker requests and enhance performance has been enabled <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1358060">bug 1358060</a>.
   </li>
   <li>Various security and general platform fixes.
   </li>
+  <li>The ChatZilla source has been integrated into SeaMonkey and no longer
+    needs to be checked out separately if you build your own release <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1551033">bug 1551033</a>.
+  </li>
+
 </ul>
 
 <p>
@@ -127,8 +133,7 @@ for new information.
   </li>
   <li>TLS 1.3 is the default SSL 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>Support for all NPAPI plugins like Flash, Java and Silverlight has been removed.
     For displaying pdf files in the browser you can use
     <a href="https://github.com/IsaacSchemm/pdf.js-seamonkey/releases/"> pdf.js-seamonkey</a>
     from Isaac Schemm.
@@ -275,17 +280,22 @@ Please read this before reporting any new bugs.
     For newer distributions you probably need the Linux x64 version.
   </li>
 
-  <li>Lightning or one of the distributed extensions is not showing up or is
-    disabled under Add-ons.
-    <br> If the extension is disabled and can not be enabled deinstall it. If
-    it does not show up after restart do the following:
+  <li>Lightning or one of the distributed extensions is disabled under Add-ons.
+    <br> Starting with SeaMonkey 2.53.7b1 the distributed extensions can no
+    longer be removed. If you have previously enabled it then under some
+    circumstance it might be disabled during the upgrade process. If the
+    extension is disabled and can not be enabled then an old or incomaptible
+    version is still present in your profile.
+    <br> To clean out old versions use the following instructions:
     <ul>
       <li>Enter "about:config" in the location bar.</li>
       <li>Enter "extensions.installedDistroAddon" in the search field.</li>
-      <li>Reset the key of the extension not showing up using the popup menu
-         with the mouse. If in doubt just reset all keys, but this might bring
-         back previously uninstalled distributed Add-ons.</li>
+      <li>Reset (delete) all keys found.</li>
+      <li>Open the Add-ons Manager. If the "remove" button is shown for the
+      disabled extension use it. Stored data like your personal calendars will
+      not be removed by this action.
       <li>Restart SeaMonkey.</li>
+      <li>Disable any distributed extension you do not wish to use.</li>
     </ul>
   </li>
   <li>Unable to connect to secure sites and a certificate error is shown.
@@ -358,7 +368,8 @@ Please read this before reporting any new bugs.
     Additionally, running MailNews with local folders and POP3 mail filters may
     produce summary files that are not correctly read by previous versions of
     SeaMonkey. If you decide to go back to a previous version of SeaMonkey, you
-    should do it from a profile backup only.
+    should do it from a profile backup only. Stored passwords will also be
+    unavailable.
   </li>
   <li>After creating a news account through clicking a news URL, the MailNews
     account wizard may be broken (the account type will always be News). To
@@ -369,7 +380,8 @@ Please read this before reporting any new bugs.
   </li>
   <li>WebRTC has been disabled by default. It needs an add-on to enable it per
     site. See the
-    <a href="https://github.com/IsaacSchemm/webrtc-permissions-ui-toggle">webrtc-permissions-ui-toggle add-on</a>.
+    <a href="https://github.com/IsaacSchemm/webrtc-permissions-ui-toggle">
+    webrtc-permissions-ui-toggle add-on</a>.
   </li>
   <li>Web pages may appear differently in the MailNews feed reader than in the
     browser (<a href="https://bugzilla.mozilla.org/show_bug.cgi?id=662907">bug
@@ -406,7 +418,9 @@ Please read this before reporting any new bugs.
   <li>Mac:
     <ul>
       <li>The scrollbar is not always visible on some websites under recent
-        macOS versions (10.15 upwards) see <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1684651">bug 1684651</a>.
+        macOS versions (10.15 upwards) see <a
+        href="https://bugzilla.mozilla.org/show_bug.cgi?id=1684651">
+        bug 1684651</a>.
       </li>
       <li>You might not be able to install SeaMonkey under recent macOS
         versions. In this case please read <a