Fix JSON examples in docs

Hi,

This patch fix the wrong examples in funcs.sgml introduced by the commit:

http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=a570c98d7fa0841f17bbf51d62d02d9e493c7fcc

regards
--
Dickson S. Guedes
mail/xmpp: guedes@guedesoft.net - skype: guediz
http://github.com/guedes - http://guedesoft.net
http://www.postgresql.org.br