Bug 1824833 - Revise webext dictionary support. r=me

src/releases/seamonkey2.53.16/index.en.html

@@ -267,12 +267,6 @@ note the following warnings and advice regarding extensions:</p>
   <li>The latest working version of NoScript Classic 5.x can be found
     <a href="https://noscript.net/getit">here</a>.
   </li>
-  <li>Dictionaries in WebExtension formats do <b>not</b> work, even though
-    they appear to install correctly. Support for them will be added at a
-    later date. Please install the latest classic version from the dictionary
-    history or unpack the dictionary inside the WebExtension package into your
-    /dictionaries directory.
-  </li>
   <li>Lightweight themes are no longer provided on the SeaMonkey Add-ons site.
   </li>
   <li>Full theme add-ons may need changes because of user interface and internal
@@ -376,8 +370,8 @@ Please read this before reporting any new bugs.
     popular add-ons like NoScript and uBlock Origin are no longer shown because
     of this on the SeaMonkey add-ons website. You can usually get compatible
     versions from the manufacturers site. WebExtensions support is a planned
-    feature for 2.57. For dictionaries please install the latest non webext
-    version.
+    feature. Dictionaries and language packs in the WebExtensions format are
+    supported.
   </li>
   <li>The SSL 3.0 encryption protocol is no longer supported due to
     security concerns (<a
@@ -471,7 +465,7 @@ Please read this before reporting any new bugs.
       </li>
     </ul>
   </li>
-  <li>Mac:
+  <li>macOS:
     <ul>
       <li>The scrollbar is not always visible on some websites under recent
         macOS versions (10.15 upwards) see <a