plscheme - htdocs: Modify exception handling documentation to catch a

Log Message:
-----------
Modify exception handling documentation to catch a specific error instead of a
global 'query-exception.

Modified Files:
--------------
htdocs:
index.html (r1.13 -> r1.14)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plscheme/htdocs/index.html.diff?r1=1.13&r2=1.14)