mods of #477 fixing help example and trying to fix anchors

rrdtool help example was clarified
and i'm trying to fix the html anchor here, but dont know how could i check if it's working or not. Googled and read http://perldoc.perl.org/perlpodspec.html still dont have a clue what does it say.
Merge pull request #483 from phpmoli/patch-6

mods of #477 fixing help example and trying to fix anchors