Minor updates to CAPTCHA Findings document

I've added some references and discussion to the first section of the document, based on papers that I've read.
Please see http://w3c.github.io/rqtf/captcha-notes.html


________________________________

This e-mail and any files transmitted with it may contain privileged or confidential information. It is solely for use by the individual for whom it is intended, even if addressed incorrectly. If you received this e-mail in error, please notify the sender; do not disclose, copy, distribute, or take any action in reliance on the contents of this information; and delete it from your system. Any other use of this e-mail is prohibited.


Thank you for your compliance.

________________________________

Received on Monday, 22 May 2017 19:36:05 UTC