docs: tune RTD to display lists with disc and left margin
    
    RTD default theme removes discs from the section list items which makes
    design pages look strange. Add them back via small CSS override.
    Also, add 1em on the left side of the disc to provide visual cue that
    this is a list item.
    
    Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Francisco Trivino <ftrivino@redhat.com>
    Reviewed-By: Sumit Bose <sbose@redhat.com>