DOCSP-15383 reposition hidden directive

Author: andf-mongodb

source/reference/read-concern-available.txt

@@ -1,6 +1,8 @@
 .. default-domain:: mongodb
 
-.. .. class:: hidden
+.. class:: hidden
+
+   .. readconcern:: "available"
 
 ============================
 Read Concern ``"available"``
@@ -10,8 +12,6 @@ Read Concern ``"available"``
    :description: Using read concern available returns data with no guarantee that the data has been written to a majority of the replica set members (i.e. may be rolled back).  Read concern available can return orphan documents. 
    :keywords: read concern, available read concern, read isolation
 
-.. readconcern:: "available"
-
 .. versionadded:: 3.6
 
 A query with read concern ``"available"`` returns data from the instance