DOCSP-18001 fixed snapshot reference (#6030)

Co-authored-by: Jocelyn Mendez <jocelyn.mendez@Jocelyns-MacBook-Pro.local>

Author: jocelyn-mendez1

source/reference/parameters.txt

@@ -3770,7 +3770,7 @@ Storage Parameters
 
    The minimum time window in seconds for which the storage engine keeps
    the snapshot history. If you query data using read concern
-   :readconcern: snapshot and specify an
+   :readconcern:`"snapshot"` and specify an
    :ref:`atClusterTime <atClusterTime>` value older than the specified
    ``minSnapshotHistoryWindowInSeconds``, :binary:`~bin.mongod` returns
    a ``SnapshotTooOld`` error.