Log Message:
-----------
Fix "Overall Page Layout" table. The second row should be ItemIdData, not
ItemPointerData.
Modified Files:
--------------
pgsql/doc/src/sgml:
storage.sgml (r1.20 -> r1.21)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/storage.sgml?r1=1.20&r2=1.21)