[krbdev.mit.edu #7640] Clarify that kdc.conf and krb5.conf are merged

[Tom Yu via RT]

This went to #7460 by mistake:

commit f3c50244f6d6967dff4e3158408f71efb3a5c665
Author: Ben Kaduk <kaduk at mit.edu>
Date:   Mon May 20 13:04:32 2013 -0400

    Clarify that kdc.conf and krb5.conf are merged
    
    These two files are merged into the profile for KDC applications
    
    (cherry picked from commit e818d27a372d021bc6025e7bce867ed06a8fc1ad)