Why don't you quote the website accurately?  It does not say anything about providing documents regarding citizenship, residency or felony status!

Here is what it does say:

The system will check with the California DMV to ensure that your signature is on file. If it is, it will be added to your registration and you may submit it at the end of the process. 

If your signature is NOT on file, your information will be sent to your local county elections board. Print the information you filled out online, sign the application, and mail it to the address specified on the form. An official will contact you once they've received all of your information. 

http://www.dmv.org/ca-california/voter-registration.php