One-time PR for Doc Reviews

@croche-okta @wdawson-okta @srinivasanagandla-okta @stsai-okta @lboyette-okta @hoanguyen-okta @karlmcguinness-okta @cwu-okta @tthompson-okta @eklein-okta

Hi team,

Since the material has been pushed to master, this pull request is a little unusual. Please add any comments to the docs here by the end of the day Monday, September 29, 2014. I will make changes and create a new branch and a new PR for the changes. Then, I will discard this PR. 

Please ping me if this doesn't work for you.

Thanks,
Evan
I would reword:
>(MFA) provides an additional layer of security when authenticating users by requiring a factor in addition to the primary password (for example a temporary one-time password or SMS passcode). The Auth API supports user enrollment in the various MFA factors enabled by the administrator, as well as the MFA challenge based on your security policy.