Remove link to google group

index.html

@@ -163,10 +163,10 @@
 
   <p>Discussion around the project is done on
   a <a href="https://discuss.codemirror.net">discussion forum</a>.
-  There is also
-  the <a href="http://groups.google.com/group/codemirror-announce">codemirror-announce</a>
-  list, which is only used for major announcements (such as new
-  versions). If needed, you can
+  Announcements related to the project, such as new versions, are
+  posted in the
+  forum's <a href="https://discuss.codemirror.net/c/announce">"announce"</a>
+  category. If needed, you can
   contact <a href="mailto:marijnh@gmail.com">the maintainer</a>
   directly. We aim to be an inclusive, welcoming community. To make
   that explicit, we have