Update server/replica installer man pages
    
    Since AD trust installer is now a part of composite installers, their
    man pages were updated with separate section documenting relevant AD
    trust-related option descriptions.
    
    https://fedorahosted.org/freeipa/ticket/6630
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>
    Reviewed-By: Jan Cholasta <jcholast@redhat.com>