I wrote a brief introduction to Perl from philosophy to pragmatic efficacy. It's available free online:

http://modernperlbooks.com/books/modern_perl_2014/

It works best with at least six months practical experience in any programming language.

From the article: "You don't have to be an experienced Perl programmer, CPAN author, or githubber. The goal is to help others, possibly learn something, and hopefully have a bit of fun."

It might be possible to help with e.g., documentation (which could also be taken as an opportunity to learn just enough Perl to read less-documented code).

No, it's not. Several people have signed up saying "I don't know Perl, but this seems like a good opportunity to start learning it".