pages/yubikey: remove note on setting secontext
    
    The access to the ~/.yubico directory is done using the PAM module, not
    sshd directly. PAM sets the context of that directory to auth_home_t
    which PAM is allowed to access. No need to set the context to
    ssh_home_t.
    
    Apart from that using chcon is a volatile operation and not intended for
    persistent changes which was the intent of the note though. The label
    would be reset in a system recovery scenario.