How to enable this in 5.3, forgotten password may receive a secure link?

[Yan Zhou]

Hello,

CAS 5.3 has "forgot password" link on the login page, that link takes to an external site that does not yet exist. 

On the other hand, CAS 5.3 doc says this: Those who have forgotten their account password may receive a secure link with a time-based expiration policy at their registered email address and/or phone.

How do I enable this? in other words, when user clicks "forgot password", it triggers a subflow that sends a link to user's email address, etc.?  Is this already part of CAS?

Thx!

Yan