Modify XFS rec to mention that it is for data bearing nodes

Author: jeff-allen-mongo

source/administration/production-notes.txt

@@ -531,9 +531,9 @@ When running MongoDB in production on Linux, you should use Linux
 kernel version 2.6.36 or later, with either the XFS or EXT4 filesystem.
 If possible, use XFS as it generally performs better with MongoDB.
 
-With the :ref:`WiredTiger storage engine <storage-wiredtiger>`, use of
-XFS is **strongly recommended** to avoid performance issues that may
-occur when using EXT4 with WiredTiger.
+With the :ref:`WiredTiger storage engine <storage-wiredtiger>`, using
+XFS is **strongly recommended** for data bearing nodes to avoid
+performance issues that may occur when using EXT4 with WiredTiger.
 
 With the :ref:`MMAPv1 storage engine <storage-mmapv1>`, MongoDB
 preallocates its database files before using them and often creates