pgsql: Add URL for: * Consider increasing the number of default

Log Message:
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Add URL for:

* Consider increasing the number of default statistics target, and
reduce statistics target overhead

Also consider having a larger statistics target for indexed columns
and expression indexes

http://archives.postgresql.org/pgsql-general/2007-05/msg01228.php

Modified Files:
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pgsql/doc:
TODO (r1.2297 -> r1.2298)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/TODO?r1=1.2297&r2=1.2298)
pgsql/doc/src/FAQ:
TODO.html (r1.806 -> r1.807)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/FAQ/TODO.html?r1=1.806&r2=1.807)