Log Message:-----------Add pg_upgrade docs about binary compatibility, per Robert Haas.
Modified Files:-------------- 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)
