Document login.links.xyz properties and defaults

Nowhere in cf-release is it mentioned that the 3 available login.links.xyz 
properties are and what their default values are. This commit brings across 
the current default values that login-server itself provides if 
login.links.home or login.links.passwd or login.links.signup are not
provided.

They are commented out so as to not force properties.login to be set if the
deployment file doesn't want it.