pgsql: Mention Stefan Kaltenbrunner as contributor for text search

Log Message:
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Mention Stefan Kaltenbrunner as contributor for text search because of
psql work.

Modified Files:
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pgsql/doc/src/sgml:
release.sgml (r1.565 -> r1.566)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/release.sgml?r1=1.565&r2=1.566)