Log Message:
-----------
Update autovacuum_freeze_max_age documentation to mention that the
default is low because of pg_clog file removal.
Backpatch to 9.0.X.
Modified Files:
--------------
pgsql/doc/src/sgml:
config.sgml (r1.307 -> r1.308)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/config.sgml?r1=1.307&r2=1.308)