I guess there’s a small but significant typo in that KB article.
Instead of tail -f +/var/log/web.log it should read tail -f ~/var/log/web.log, i.e. tilde instead of plus character, so it references the log below the site dir, not the system-wide log (which probably doesn’t exist at that path anyway)
@mschlenker: not sure if that might be something for you to check/fix?