doc: fix deprecated alias description in cluster

Refs: #36478

PR-URL: #41618
Reviewed-By: Mestery <mestery@protonmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: tniessen

doc/api/cluster.md

@@ -855,7 +855,6 @@ deprecated: v16.0.0
 -->
 
 Deprecated alias for [`cluster.isPrimary`][].
-details.
 
 ## `cluster.isPrimary`