You can also use perldoc perldoc to read about perldoc itself.

And a minor nitpick: perldoc -q <search item> looks for the topic in the FAQ. So it's possible to miss something that is in the perldoc using the -q switch if it's not in the FAQ. qx is one example (although admittedly it took me a bit of searching to find this example).

Specifically, perldoc -q qx gives me the output No documentation for perl FAQ keyword 'qx' found even though perldoc -f qx produces Generalized quotes. See the section on "Regexp Quote-Like Operators" in the perlop manpage.