pgsql: Move a few items into migration from the main changes section.

Log Message:
-----------
Move a few items into migration from the main changes section. Indent
8.3 consistently.

Modified Files:
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pgsql/doc/src/sgml:
release.sgml (r1.523 -> r1.524)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/release.sgml?r1=1.523&r2=1.524)