New URL for zxcvbn Password Checker

Several places in Take Control of Your Passwords—on pages 34, 136, and 143—I mention an open-source password strength calculator called zxcvbn. Unfortunately, the links in the book are broken because the location of the files changed. You can now access the password checker at this link: zxcvbn. I’ll correct the link the next time I update the book, which I expect will be relatively soon.