Doc review 8 26 2

@tthompson-okta @croche-okta @stsai-okta @srinivasanagandla-okta @lboyette-okta @wdawson-okta @hoanguyen-okta @karlmcguinness-okta @cwu-okta 

Mostly for Trevor--reset factors API doc.
We need to also this this link relation to http://developer.okta.com/docs/api/rest/users.html#links-object.  It is important to indicate that the link relation only shows up the user has enrolled in a factor.