pgsql: Add documentation for pulling the CVS repository using rsync, and

Log Message:
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Add documentation for pulling the CVS repository using rsync, and
mention cvsup last.

Modified Files:
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pgsql/doc/src/sgml:
cvs.sgml (r1.41 -> r1.42)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/cvs.sgml.diff?r1=1.41&r2=1.42)