Log Message:
-----------
Update journaling performance docs based on comments by Michael Renner.
Modified Files:
--------------
pgsql/doc/src/sgml:
wal.sgml (r1.54 -> r1.55)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/wal.sgml?r1=1.54&r2=1.55)