Update instructions for disabling and re-enabling SELinux
    
    The kernel functionality that allowed to disable SELinux by changing
    /etc/selinux/config is now deprecated and will be removed in F34 [1].
    While setting SELINUX=Disabled will still lead to a similar state even
    after the removal, it is better to guide users to disable SELinux via
    kernel boot parameters, which will actually disable SELinux completely
    (as in no SElinux code is executed by the kernel).
    
    [1] https://fedoraproject.org/wiki/Changes/Remove_Support_For_SELinux_Runtime_Disable
    
    Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>