pgsql: Adjust example to reduce confusion between a tsvector column and

Log Message:
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Adjust example to reduce confusion between a tsvector column and
an index, per Simon.

Modified Files:
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pgsql/doc/src/sgml:
textsearch.sgml (r1.34 -> r1.35)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/textsearch.sgml?r1=1.34&r2=1.35)