pgsql: In text search docs, properly use indexterm _zone_ only when we

Log Message:
-----------
In text search docs, properly use indexterm _zone_ only when we want an
entire section, per Peter.

Modified Files:
--------------
pgsql/doc/src/sgml:
datatype.sgml (r1.208 -> r1.209)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/datatype.sgml?r1=1.208&r2=1.209)
func.sgml (r1.390 -> r1.391)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml?r1=1.390&r2=1.391)
textsearch.sgml (r1.11 -> r1.12)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/textsearch.sgml?r1=1.11&r2=1.12)