It will be tedious, but the only answer I can suggest is for you to print the help pages one by one to PDF. Make your own document from the website. I don't believe that you will find a simple way.
Hiroto has it right - the printer icon offers the PDF book in a greatly less tedious way than I suggested .
It's 6.7 MB in PDF format. Send me an e-mail and I'll send you the file by return e-mail.