pgsql: Only use SGML indexterm "zone" when we want to get the entire

Log Message:
-----------
Only use SGML indexterm "zone" when we want to get the entire section.

Some alignment cleanups.

Modified Files:
--------------
pgsql/doc/src/sgml:
extend.sgml (r1.35 -> r1.36)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/extend.sgml?r1=1.35&r2=1.36)
func.sgml (r1.391 -> r1.392)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml?r1=1.391&r2=1.392)
libpq.sgml (r1.239 -> r1.240)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/libpq.sgml?r1=1.239&r2=1.240)