Log Message:
-----------
Add mention that Shared Disk Failover can use file system mirroring of
the mirroring is consistent.
Modified Files:
--------------
pgsql/doc/src/sgml:
high-availability.sgml (r1.2 -> r1.3)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/high-availability.sgml.diff?r1=1.2&r2=1.3)