pages/yubikey: reformat flags of ykpersonalize
    
    The man page of ykpersonalize uses a confusing format for providing
    option flags. After tests although not documented in the man page it is
    also possible to use an alternative format using spaces between option
    flag and value. Also to note: the negative form of an option flag uses a
    '-' symbol right in front of the value.
    
    Also the slot selector -1 or -2 has to be supplied before any option
    flag.