Add Warning Message to Login page

[ChengShi-1]

Overview of the Feature Request
Adding a note/alert on the Harvard SPA login page to clarify that some of the available login options are not supported.
JSF example:

What kind of user is the feature intended for?
(Example users roles: API User, Curator, Depositor, Guest, Superuser, Sysadmin)
SPA Users

What inspired the request?
CILOGON page provides too many options that may cause confusion for users

What existing behavior do you want changed?

Any brand-new behavior do you want to add to Dataverse?

Any open or closed issues related to this feature request?