pgsql: Update HOT README about when single-page vacuums happen.
Log Message:
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Update HOT README about when single-page vacuums happen.
Modified Files:
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pgsql/src/backend/access/heap:
README.HOT (r1.6 -> r1.7)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/heap/README.HOT?r1=1.6&r2=1.7)