plscheme - htdocs: Add a new bullet to the features listing about

Log Message:
-----------
Add a new bullet to the features listing about recently implemented caching
mechanism.

Modified Files:
--------------
htdocs:
index.html (r1.16 -> r1.17)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plscheme/htdocs/index.html.diff?r1=1.16&r2=1.17)