DOCSP-14923 fix deprecated directive for NextGen

Author: andf-mongodb

source/reference/method/db.collection.ensureIndex.txt

@@ -6,11 +6,23 @@ db.collection.ensureIndex()
 
 .. method:: db.collection.ensureIndex(keys, options)
 
-.. admonition:: Removed in 5.0
-   :class: note
+.. note:: Removed in 5.0
 
-   :method:`db.collection.ensureIndex()` has been replaced by 
-   :method:`db.collection.createIndex()`.
+   .. include:: /includes/fact-mongo-shell-method.rst
+
+   .. deprecated:: 3.0
+
+      :method:`db.collection.ensureIndex()` has been replaced by 
+      :method:`db.collection.createIndex()`.
+
+   Creates an index on the specified field if the index does not
+   already exist.
+
+Additional Information
+----------------------
+
+- Use :method:`db.collection.createIndex()` rather than
+  :method:`db.collection.ensureIndex()` to create new indexes.
 
 .. seealso::