A couple of points I noticed while doing my backport to info:
1. We start by saying "you can just use require," but then we say "you only need to load asdf.lisp." I think it would be better to say "if this require trick works, you can skip over the section about loading asdf."
2. We might want to say "you might want to install ASDF yourself if you want to get a particular version of ASDF."
HtH, r