Log Message:
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Add pg_upgrade docs about binary compatibility, per Robert Haas.
Modified Files:
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pgsql/doc/src/sgml:
pgupgrade.sgml (r1.10 -> r1.11)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/pgupgrade.sgml?r1=1.10&r2=1.11)