Docs: Update jQuery CDN related info from `faq.md`

Update documentation to include the information from the recent
jQuery team announcement:

   "To mitigate the risk of “breaking the web”, the jQuery team
    decided back in 2013 that jquery-latest.js could not be
    upgraded to the 2.0 branch even though that is technically
    the latest version. There would just be too many sites that
    would mysteriously stop working with older versions of Internet
    Explorer, and many of those sites may not be maintained today.

    As jQuery adoption has continued to grow, even that safeguard
    seems insufficient to protect against careless use of
    http://code.jquery.com/jquery-latest.js. So we have decided to
    stop updating this file, as well as the minified copy, keeping
    both files at version 1.11.1 forever ...

    The Google CDN team has joined us in this effort to prevent
    inadvertent web breakage and no longer updates the file at
    http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.js. That
    file will stay locked at version 1.11.1 as well."

  (from: http://blog.jquery.com/2014/07/03/dont-use-jquery-latest-js/)

Ref: h5bp/html5-boilerplate#1554