doc/designs: fix formatting in LDAPI autobind design
    
    Even though specifying 'raw' format is allowed, this breaks Read The
    Docs which is not able to complete the full build of documentation and,
    therefore, doesn't publish an updated documentation.
    
    Pushed under one-liner rule.
    
    Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>