LUDOC-160 lustreproc: Added note, reordered content in Monitoring section for clarity.

LUDOC-160 lustreproc: Added note, reordered content in Monitoring section for clarity.

Brett Lee has confirmed the content issues in this ticket were addressed in
LUDOC-168 (LustreProc rework). Changes made now include adding a note to clarify
how extents_stats and offsets_stats are enabled and minor rearrangements
to text for clarity.

Signed-off-by: Linda Bebernes <linda.bebernes@intel.com>
Change-Id: I451cad9dfe67d504d6c90faf992595e0f199e043
Reviewed-on: http://review.whamcloud.com/7763
Tested-by: Hudson
Reviewed-by: Brett Lee <brett.lee@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>