The documentation on this site is for an old version of Perl.

But no version of Perl would be able to match whatever people here have. If you want to get accurate documentation for what you have, you need to consult local documentation on your machine. Nothing else has a hope of being in sync with you. Which is why I prefer to tell people to do as I do and use your perldoc command to consult documentation, rather than going to websites that don't match what you have installed. So start with the following three:

perldoc perldoc
perldoc perl
perldoc perlguts
[download]

and start reading.